94 PROFESSOR O. BUTSCHLI. 



with dilute acetic acid it appears as a vesicular nucleus, 

 with a large and dark irregular sheath containing nucleoli. 



The nucleus lies in a space which is remarkable for its 

 clear and transparent nature ; it occupies almost the entire 

 breadth of the anterior extremity, but rapidly narrows as it 

 passes backwards, and in large specimens it can usually be 

 traced only as far as the centre of the body (fig. 21 a), whilst 

 in smaller examples it extends almost to the hinder end of 

 the body (fig. 27 b). In the larger specimens also a deli- 

 cate transparent band runs along the middle line of the 

 body to the posterior end as a prolongation of the anterior 

 light space. Round this clear space at the anterior end, 

 which is triangular when seen in optical section, is a 

 thick envelope of a denser and darker plasma, which is 

 tolerably sharply bounded off from the remaining proto- 

 plasm (fig. 21 a). The body, therefore — at least, in the larger 

 individuals — is divided into two portions, of which the 

 anterior is somewhat shorter than the posterior. After treat- 

 ment with dilute acetic acid the two segments are sometimes 

 very clearly separated from each other, whilst there appears 

 between them a space filled with fluid brought about by the 

 varying contraction due to coagulation. 



The hinder and larger half of the organism consists of a 

 transparent granular protoplasm. It encloses a larger or 

 smaller number of granular contents, Avhich, so far as the 

 author can judge, consist chiefly of food particles. In 

 the organisms examined this part of the body usually 

 contained a number of very dark, round, or oval granules, 

 of a high refractive index, closely packed together, such as 

 exist in quantities in the intestine of the cockroach ; 

 they are probably starch granules, but they have not been 

 examined chemically. Individuals are occasionally found, 

 which are very much smaller, and are free from such granular 

 contents. A protoplasmic thread was often seen at the pos- 

 terior end, which trailed as a tail-like prolongation of the 

 body substance. Sometimes, also, numerous bodies of a con- 

 siderable size, like those within, adhered to the outside of the 

 hinder end of the organism, giving rise to the supposition 

 that the hinder end took part in some undefined way in the 

 ingestion of food ; and this is rendered more probable by the 

 fact that the peculiarly constructed anterior end is always 

 found to be entirely free from food contents. No contractile 

 vacuole is discoverable. Vacuoles are only very rarely found 

 in the substance of these organisms ; the author has, himself, 

 observed them in only two cases, in neither of which was 



