PUBLIC RECORD OFFICE
Reference :-
mmimmi MC.O. 885
23 PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE COPYRIGHT PHOTOGRAPH-NOT TO BE REPRODUCED PHOTOGRAPHIC-
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without being actually in contact; these were probably indications of agglomeration. A few trypanosomes seen of normal slender build, vibrating actively and travelling slowly, with the hinder end appearing to drag. At 5 p.m. a few trypanosomes seen travelling quite fast; otherwise no change. The preparation was then smeared off, about six hours after it was put up. In the stained film crithidial forms were found, some dividing; also long trypanosomes, apparently "shooters," and knotted trypanosomes with all stages in the degeneration of these into rounded forms, finally lacking a flagellum.
The only indications which could be drawn from this first series of experiments were negative-i.e., they left Professor Minchin under the impression that the pas- sage of trypanosomes directly into fresh rat's blood did not result in further develop- ment of the final (propagative) forms. Apparently the stumpy forms became knotted shooters were regarded by him, I believe, as and gradually degenerated. The " trypanosomes developing into the final form-i.e., transitional between the crithidial and the stumpy trypanosome forms-and not as a further stage in development of the latter Of course, the experiments were not exhaustive; and, moreover, in this first series the hanging drops were not kept in an incubator at blood temperature, as was the case in subsequent experiments. Nevertheless, the results appeared to negative any idea that the trypanosomes pass immediately into the blood stream through a minute fissure or lesion, for instance, in the rat's mouth.
In another set of experiments the rectum of the infected flea was put up with either stomach-contents or duodenal-contents from a rat. This series was distinctly negative, all forms of the trypanosome rapidly becoming motionless and dying off, This although the preparations were kept in an incubator at blood temperature. result was a strong indication that the trypanosomes do not normally pass directly so far down the alimentary tract, or at any rate that, if they do so, they undergo no further development, but die off. On the other hand, in a third series of experi- menta, a distinct indication was obtained of the stimulating effect of the saliva of the rat upon the trypanosomes.
The
The following is the record of a typical experiment with saliva :-Numerous crithidias and a few trypanosomes were seen in the rectum of the dea before the preparation was made; the rectum was mounted in a hanging drop with saliva from a clean råt at 11.25 a.m. Immediately after mounting five trypanosomes were seen and their position marked. They were very sluggish, almost motionless. preparation was then put into the warm incubator. At 2.30 p.m. it was taken out and examined. At once active trypanosomes were seen. Eight such were noted, most of them travelling actively. None of those marked in the morning were in The their places. The crithidias in the clumps were also moving actively. preparation was then returned to the incubator. At 4.30 it was again examined. Others Many slender, very active trypanosomes were seen, some travelling fast. were observed butting with their hinder ends against small pieces of tissue. Most One of the trypanosomes seen, in fact, were congregated round fragments of tissue. such remained, during the half-hour it was under observation, attached by its hinder end to a portion of a malphigian tubule (accidentally in the preparation, removed with the rectum). One trypanosome was seen travelling slowly, with a body like a Some globule at its hinder end; this was probably a recurved form (cf. below). trypanosomes appeared more crithidial or transitional in form; these were either vibrating still or else motionless. The drop was then smeared and fixed. In the stained preparation a fair number of crithidias were found, which appeared for the most part coarsely granular and apparently degenerating. The trypanosomes were of various types, but many undoubtedly recurved; one was attached to a fragment of tissue.
Although, as already pointed out, Professor Minchin was only at the commence- ment of these experiments when he had to relinquish them, I know that, nevertheless, be attached considerable importance to the occurrence of the characteristic recurved type of trypanosome in this last series, because it is just such a type which is the earliest stage in the development of the remarkable intracellular multiplicative phase in the flea's stomach. He had, in fact, strong feeling that a similar type of intracellular multiplication would be found also to occur early in the life-cycle of the trypanosome in the rat. And even while he was making this discovery of the early development of recurved forms he received some photographs from Dr. Coles, of Bournemouth, which this gentleman had sent for Professor's opinion upon them. showing both similar recurved forms and what were in all probability actual stages
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of intracellular (1) multiplication found in the lung of a naturally infected rat. Professor's own first-formed tentative opinion was that this intracellular multipli- cation might be the first type of multiplication undergone by the trypanosomes after entering the rat. He proceeded, therefore, to examine the lungs of rats which had been exposed to infection (and then removed from the flea-cage), after a varying number of days had elapsed. He examined such rats after three and four days (i.e., before the trypanosomes were showing in the blood) and also after they had just begun to appear. The lungs were examined both in the fresh condition and after sections made from them had been cut and stained. He did not, however, succeed, in these first attempts, in finding any indications of this intracellular multiplication. Dr. Coles, in a quite recently published account of his observations, says that the recurved and multiplicative forms which he found in the lung occurred when there were numerous trypanosomes in the blood. It is possible, therefore, that this lung- If. multiplication may be secondary to the ordinary multiplication in the blood. however, as is, perhaps, more probable (bearing in mind Professor's discovery of the early development of recurved forms), the early course of development in the rat is parallel to that in the flea, the intracellular (?) lung-multiplication will be found to be the first type; but it may continue while the trypanosomes are spreading and multiplying in the blood, just as the intracellular multiplication in the flea's stomach continues for some time while the crithidial forms are beginning to develop and pass backwards into the rectum. How soon the trypanosomes reach the lung. and what course they take to that organ, Professor Minchin was not able to ascertain; he was, however, of the opinion that they do not pass as far down the alimentary canal as the stomach.
General.-Professor Minchin had been elected to the Presidency of the Zoo- logical Section of the British Association meeting in September last, and the last work he was able to do was the preparation of his presidential address on the "Evolu- tion of the Cell." Unfortunately, when the time came he was too ill to deliver it himself, or even to be present when it was read. During the months of January, February, and March, 1915, Professor Minchin gave his usual annual course of lectures. The course comprised fourteen lectures, twice weekly, on "Development and Life-Cycles in the Protozoa," each lecture being followed by a demonstration of Owing to the war the microscopic exhibits illustrating the subject dealt with. attendance was, of course, considerably less than usual. The average number present was eleven, which was, indeed. more than we expected.
The departmental work is also referred to at the end of my own report, following.
H. M. WOODCOCK.
November, 1915.
ON
DURING WORK DONE
THE YEAR
ENDING
REPORT BY H. M. WOODCOCK, D.Sc. (LONDON), ASSISTANT TO THE UNIVERSITY
PROFESSOR OF PROTOZOOLOGY, 30TH JUNE, 1915.
(a) Research. My research work has dealt with two subjects (1) coprozoic Antarctic flagellates and (2) the parasitic protozoa collected by the "Terra Nova` Expedition.
(1) The greater part of my time has been occupied with the comprehensive study of the simple flagellates which pass through the active phases of their life-cycle in moistened dung or fæces (of ruminants, such as the goat and sheep). Following a suggestion of Professor Minchin, I use the term "coprozoic" to denote the fauna with this characteristic habitat. All such forms, it is to be noted, pass through the alimentary tract of the goats and sheep in a quiescent, encysted state. The copro- zoic fauna of these ruminants is entirely distinct from the truly parasitic fauna of the same animals. The latter is mainly composed of certain characteristie ciliates, which are never found active in the dung. A few flagellates also occur in the rumen, but these are of quite different type from those occurring active in the dung. Many of the coprozoic flagellates, at all events, can be cultivated, I have found, on various nutrient media. The absolute distinction between the flagellate types found in the fæces and those parasitic in the alimentary canal (e.g., Spheromonas, Piromonas, Trichomonas, Callimastiz) affords striking corollary evidence in favour of the view that the parasitic Entamoeba (e.g., those of dysentery) are distinct forms from the fæcal or cultural Amabæ.