6o8 Microscopic Organisms in Blood of Man and Animals. Impart hi. 



a recent paper by Biitschli,* in which he refers to a flagellated parasite which he has 

 often observed in the intestinal canal of a free nematode (Trilobus gracilis). He 

 refrains from giving it a name owing to the uncertainty which exists with regard to 

 organisms of this kind. He generally found them in large numbers, often forming 

 stellate colonies owing to their being attached by their non-flagellated-ends. They 

 readily became detached and then presented a somewhat spindle-shaped body, about 

 11/i in length and with a somewhat thick flagellum about double this length, so that 

 the total length of the protozoon would be 33/x, something more than half of the 

 length of the flagellated organism found in the rat's blood. Near the base of the fla- 

 gellum of Biitschli's protozoon a contractile vacuole could be distinguished, but I have 

 not been able to detect any such vacuole in these rat-hsematozoa . 



Seeing that the blood of such a large proportion of rats contain these organisms, 

 I can hardly suppose that their existence has hitherto escaped notice, unless it be that 

 rats in Europe do not harbour like parasites. Davainef in the recent edition of his 

 work makes mention that M. Chaussat had found minute nematodes in the blood of a 

 black rat (Mus rattus), but I have not seen any nematode in the blood of rats in this 

 country. In the tissues, bladder, etc., of rats such parasites are very common, but 

 their description does not come within the province of this paper. 



The nearest approach to the flagellated hsematozoa of rats which I have seen de- 

 scribed is to be found in a foot-note in Dr. Bastian's " Beginnings of Life," t where it 

 is stated that Dr. Grros had seen minute worms (yerniicules) in the blood of a field- 

 mouse (mulct) which were so numerous as to cause the blood to present an animated 

 appearance; and that the blood of the mole was often found to be in a similar con- 

 dition. They were so small as to be barely visible under a power magnifying 400 

 diameters. I have not been able to obtain any minute description of these vermicules, 

 but I anticipate that it will be found that they closely resemble the flagellated protozoa 

 found in the blood of Indian rats. 



With regard to the health of the rats in which these flagellated organisms were 

 detected, there was nothing to suggest in any way that they were less healthy than 

 others not so affected, and I have repeatedly kept rats for a considerable time for the 

 "purpose of observing whether any special symptoms would be manifested suggestive of 

 the existence of such organisms in the circulation. It should be mentioned that it 

 frequently happened that the rats caught in a particular room would be affected, 

 whereas the blood of rats in another part of the building would not contain them. 

 The servants had ultimately come to recognise this, as, whenever they learnt that a 

 particular rat's blood contained the desired organisms, they diligently endeavoured to 

 secure the rest of the family. 



When it is considered that thousands of active beings of this character can exist 



* " Beitrage zur kenntniss der Flagellaten und einiger verwandten Organismen :" Zeitschr. filr wisxennch 

 Zoologie. Band XXX, Heft 2, Taf. XI, Fig. 9, Jan. 1878. 



f Traits des Entozoaires, Edit. II, pp. 11, 957 : 1877. Leuckart's " Parasiten," vol. ii, p. 636. 

 X Vol. ii, p. 338 : 1872. 



