168 



s. GOTO. 



In this tissue are imbedded all the organs hereafter to be des- 

 cribed, as also some of the organs already described. Owing to the 

 presence of the vitelline body, the mesenchyma in the anterior half 

 of the body is mainly confined to the peripheral portion, but is also 

 present in a scanty quantity between the lobes of the vitelline body 

 and the cells of which they are composed. When one takes it up for 

 study, he finds great perplexity and difficulty in making out the true 

 nature of the elements that compose it, until he compares it with the 

 mesenchyma of other allied species. In Diplozoon, it consists of a 

 fibrous substance, in which are seen nuclei each with a distinct mem- 

 brane of its own. These nuclei always enclose one or more deeply stained 

 nucleoli. The nuclei are of various size and shape. In the anterior 

 portion and generally in the anterior half of the body, they are gener- 

 ally of a comparatively small size (Figs. 7, 8, 9, 25) ; in the posterior 

 half of the body, however, they are generally of a larger size (some- 

 times having the diameter of about 0.01 mm.) and have a circular or 

 oval outline (Fig. 13). In the vicinity of the internal organs, where 

 the connective tissue is generally more or less compressed, the nuclei 

 are smaller and often fusiform in shape. Around the pharynx, the 

 fibres form a fine close net- work (Fig. H). 



Beside these elements, we see here and there, scattered apparently 

 without any regularity in the parenchyma, large vesicular bodies of a 

 circular or oval outline (Fig. 13), with a large conspicuous nucleus in 

 the centre surrounded by a mass of granular protoplasm, which on 

 close inspection betrays a fibrous structure, and which gradually 

 thins out peripherally, and leaves an empty space between it and the 

 wall. These vesicular bodies are sometimes drawn out towards one 

 end, and are very abundant in the posterior half of the body, posterior 

 to the testis. In the region situated between the ovary and the testis, 

 the mesenchyma consists of distinct cells with a granular, generally 



