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As described in my last Report (vide Cd. 7796), the first member of this copro- zoic fauna which I studied, in collaboration with Mr. Lapage, was a new type of flagellate, Helkesimastiz, of which we were able to outline the complete life-cycle, Owing to Mr. Lapage being including the important phase of conjugation. occupied with medical studies I have since continued the work alone. flagellates which have been observed are the following: Monas (probably vulgaris), Cercomonas (Cercobodo) longicauda and perhaps another species, Helkesimastix fæcicola and major, Bodo (Prowazekia) caudatus, at least two Bodo-like forms without a kinetonucleus, one of them being most probably Heteromita globosa and the other being regarded as a distinct type, Heteromastix, Spiromonas angusta, Phyllomitus undulans, Copromonas ruminantium, n. sp., and, lastly, a most elusive uniflagellate form, which appears to be new, for which I propose the name Prolepto- monas fœcicola, n.g., n. sp.

I have completed and offered to the Royal Society a memoir dealing with the results of my work so far on these flagellates, and I can here only summarize briefly what is there set forth.

The occurrence and comparative frequency of the different forms is indicated. The success (or non-success) of my attempts to cultivate them and the behaviour in culture-media is also indicated. Notes on the technique adopted are given, with special reference to the use of observation preparations, which have been of the utmost service in determining the modes of movement and the different phases of the life-cycle.

These flagellates show considerable variety and distinctness in regard to their movements. The movements furnish, in my opinion, a generic character of great importance and usefulness from the point of view of distinguishing the different types in life. Any one of the above-mentioned genera can be readily distinguished from its movements alone.

The different flagellates are then considered seriatim, and an outline is given of the observations already made upon them. In the case of two or three I have been able, so far, to make only scanty observations, and have not yet had opportunity to Where I have been successful in obtaining a follow the course of the life-cycle. good idea of the life-history my attention has been mainly directed, in the first place, to ascertaining whether syngamy (conjugation) occurs or is absent; and, where it occurs, how to distinguish between individuals undergoing conjugation and indi- viduals undergoing division. For, as is well known, most of these flagellates divide by simple binary fission, and there have been so many cases of forms regarded as exemplifying conjugation which were much more probably instances of fission that the greatest care is at first necessary in order to be certain in regard to such an Nothing but continued and repeated observations during life important matter. have enabled me to elucidate to a large extent this question of syngamy among these simple protomastigine flagellates and to be in a position to distinguish, on the broad grounds of behaviour and the morphology, whether a particular case is one of union or fission.

Influenced by our discovery of syngamy in Helkesimastix, which was soon determined when we came to study the flagellates closely, I felt sure that this pheno- menon was of far more general occurrence among these forms than was usually thought to be the case, and that the German workers (such as Klebs, Senn, and others) who derided the careful and patient work of early British workers (e.g., These English workers, Dallinger and Drysdale, and Saville Kent) were wrong.

by continued observations on the living creatures, had found conjugation to occur in many of the infusion flagellates which they studied. But, thanks largely to the bare assertions of the Germans, who never attempted to repeat the continuous and pro- longed observations on the same flagellates, pronounced scepticism grew up with regard to the correctness of the observations of the English authorities, which was quite unfounded.

I am now able to show that conjugation does occur in the case Dobell of many, probably most, of these lowly coprozoic and infusion flagellates. was the first to observe the process; but he found it in a new type, Copromonas, probably modified from a higher order, and in any case one which had not been noted by the earlier workers. Previously to our work on Helkesimastix the only reliable indication of conjugation in one of these simple, lowly forms was given two or three years ago, by Martin, for Oicomonas termo: but this case had to be regarded with some reserve, because the syngamy had not been followed in life, the surest test in the first place. I have found very similar phases in Monas vulgaris, and, from my

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general knowledge now of the process of syngamy in other of these flagellates, fol- lowed in the living creatures, it can be said that Martin was certainly right in concluding he had obtained syngamy in Oicomonas.

The remarkable feature of the question is that, just in those cases where a recent school of German workers has maintained that conjugation does take place among these protomastigine forms-i.e., in trypanosomes-such a process is here entirely lacking. Truly, it is becoming more and more apparent that the science of protozoology has not in reality benefited much of late years from German work; and I write with some knowledge of the matter, for I spent a long time finally settling in the negative (though the Germans still do not admit it!) a view of funda- 'mental importance, originating from German work, and at first generally accepted. A typical illustration of Teutonic scientific methods is afforded by the fact that, in the most recent editions of what purport to be the most comprehensive and up-to-date treatises extant on pathogenic protozoa (v. Prowazek) and pathogenic micro- organisms (Kolle and Wassermann), the halteridia and leucocytozoa are still regarded as the sexual forms of certain trypanosomes, and the piroplasmata are still said to have a flagellate phase (Breinl and Hindle's contamination-flagellate)!

Of the coprozoic flagellates mentioned above I have found syngamy in the following: Monas, Cercomonas, Helkesimastix, Spiromonas, and Heteromita globosa, and, of course, in the new species of Copromonas. Conjugation probably occurs in other forms, such as Phyllomitus, but I have not yet been able to watch them for any length of time. A very important fact is that syngamy does not occur in Bodo (syn. Prowazekia) caudatus, which is a binucleate form, as are the trypanosomes.

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There are certain important points of distinction between individuals under- going fission and those undergoing syngamy which may prove to be, I think, of general application, and consequently of great assistance in studying other of these dung- or infusion-flagellates. Division (fission) is a very rapid process, taking usually only fifteen to twenty minutes or so; syngamy, on the other hand, is invariably a long In a case where syngamy is process, lasting many hours before it is completed. occurring the double or united individual (i.e., the zygote) remains active for a In division, long period some hours with duplicated flagella of normal length. on the other hand, the individual always ceases (practically) to displace itself, for a few moments while the actual fission of the body is taking place, and the daughter- flagella are at first considerably shorter than the normal length; sometimes all signs of flagella disappear, apparently, for a brief period prior to the fission. Syngamy is usually followed directly by encystment.

I am very pleased to have obtained the conjugation in the well-known and common Cercomonas; this form has been observed and studied by many workers, and even one or two in recent years have regarded as a phase of multiplication what is in reality a characteristic stage in conjugation. The process of syngamy in this Spiromonas is a most interesting form is extremely like that in Helkesimastia. form, extremely polymorphic at different stages in the life-cycle. The earliest phase is the most minute form of flagellate I have ever seen, more like a bacillus, in fact, when seen alive. Division is usually (though not invariably) tripartite, a large, bean-like form coming to rest and forming a very delicate cyst, from which, after about twenty minutes, three daughter-individuals are liberated with great rapidity, dashing out of the field in different directions and leaving nothing but a few granules behind. The product of syngamy here is an active form-i.e., the zygote does not encyst. A remarkable fact is that I have not yet been able to observe the (resistant) cysts of this flagellate, in spite of great efforts. Phyllomitus is peculiar in that the two flagella, long and short, are united proximally by a hand, which probably functions in a manner similar to that of the undulating membrane of certain ciliates, aiding in wafting food-particles into the oral depression. thus able to confirm, for the first time, Stein's description, forty years ago, of the morphology of this interesting type. Here, again, Klebs, some few years ago, described what he considered as a species of this form, and maintained that Stein was wrong in regard to the presence of this band. Klebs was himself wrong, or else had another form under observation. The new uniflagellate type, Prolepto- monas, is an extremely active acicular form, possessing a very long single flagellum, anteriorly directed. It is very like a Leptomonas in form and general appearance, but it has no kinetonucleus and is active only in the dung-i.e., it is not a parasite. This form may well represent the ancestral type from which Leptomonas and the related series of binucleate flagellates (including the trypanosomes) are descended.

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