430 APPENDIX. 



some to the other. This explanation receives confirmation from the fact 

 of those Cysticerci which are developed in the muscular parietes of the 

 heart being of a different shape from those formed elsewhere, although 

 their structure in all other respects is precisely the same. These Cysti- 

 cerci, in the first or mermicular stage of their development, are very short 

 and thick, and of an oval shape. Their locomotive fibres, though per- 

 fectly demonstrable, are very short, and in many instances imperfect. 



" After these Cysticerci have reached the spaces between the muscular 

 fibres, their subsequent development is the same as in other situations, 

 and the perfect animals formed in the heart cannot be distinguished from 

 those formed in other muscles. I may also add, that, while in the vermi- 

 cular stage, the Cysticerci developed in the short muscular fibres of the 

 tongue, are of a shape resembling very much those of the heart. 



" The investing membrane which has just been described as covered with 

 cilia, is entirely filled with corpuscles, all of one kind, remarkably charac- 

 teristic, and differing only according to their states of development. The 

 perfect cells are best seen in the middle of an entozoon, but their mode of 

 formation, and the subsequent changes which they undergo, must be 

 examined in those parts which are increasing most rapidly, as in the 

 growing ends of an animalcule. 



" The first appearance indicative of an increase in the length of an 

 animalcule is a thinning of the investing membrane, and a separation or 

 partial detachment of the cilia-like fibres at the growing end. Next, a 

 clear space, of the form of the part which is about to be added, is percep- 

 tible a little in advance of this extremity, apparently the result of a very 

 fine membranous protrusion. This contains numerous dark molecules of 

 different forms and sizes mixed with granules more or less perfectly sphe- 

 rical : the most perfect of these globular bodies are those which are 

 nearest to the perfectly formed part of the animalcule. These corpuscles, 

 when completely formed, have a bright oily-looking aspect, and a diameter 

 of about ^o a o oth of an inch. 



" These corpuscles have the appearance of being formed by the coalescence 

 of molecules which had existed in the clear space before any corpuscles 

 were apparent, by which they are afterwards replaced. After a growing 

 end has become thus filled with these globular bodies, the terminal mem- 

 brane becomes more and more distinct, and the cilia-Hke fibres are after- 

 wards added, which are generally neither so regularly disposed, nor so 

 distinct as on other parts of an entozoon. Next, these corpuscles lose 

 their spherical form and become flattened, and lastly, they assume their 

 characteristic elliptical or reniform figure before mentioned, which they 

 retain as long as the entozoon remains in its primary muscular fasciculus. 

 This shape, however, is not essential to these corpuscles, but merely 

 results from the rounded form of the masses into which they are grouped 

 together, each corpuscle, by its convexity, forming a segment of the 

 circular outline of its respective group. These corpuscles contain very 

 fine dark granules, so variously disposed in different ones, as to present a 

 variety of appearances, such as circular or oval spaces, which might be 

 taken for nuclei or nucleoli. These collections of corpuscles make up 

 nearly the whole of an animalcule, and they frequently give to it a 

 lobulated and sometimes an obscurely annulose appearance. 



" The entozoa, as long as they remain in the primary fasciculi, retain all 

 those characters which have so far been described ; but these character 



