464 EICHAED EVANS. 



PLATE 35. 



Fig. 1. — X 1000. Portion of a section of a larva, type A, at the junction 

 of tiie larval cavity and tiie solid posterior part of the inner mass (cf. Fig. 9). 

 Below the flagellated cells (/. c.) are seen the cells with granular nuclei 

 {e.g. n.) containing a few yolk bodies, and in the interior the cells with 

 vesicular nuclei (<?. v. ti.) full of yolk bodies. The vacuole («. v.) seen in 

 the greater number of these cells is the nutritive vacuole, which blackens 

 with osmic or Hermann's fluid. The yolk bodies {y. b.) are deeply stained 

 with bleu dc Lyon, and exhibit a clear area in the centre, which in some cases 

 has a red patch in it. 



Fig. la. — x 1000. Portion of a section of thesamelarva as Fig. 1, showing 

 the layers of cells at the side of the larval cavity. Note the yolk bodies 

 (y. b.) in the cells with granular nuclei, and that ihey are few in number. 

 Note also the absence of cells with vesicular nuclei, as well as of a flattened 

 layer of cells lining the larval cavity (i. C). 



Fig. 2. — X 1000. A few cells with vesicular nuclei drawn from a larva 

 which had been preserved in Hermann's fluid. The sections were afterwards 

 partly bleached with chlorine, and owing to this process of treatment the 

 nutritive vacuoles {b. n. v.) became decolourised, presenting the same appear- 

 ance as in the previous figures. 



Fig. 3. — A cell with a vesicular nucleus which has divided into two, the 

 cell itself being as yet undivided. Note that it also represents a transitional 

 stage from a cell with a vesicular to one with a granular nucleus. The 

 transitional characters are — a few yolk bodies (y. b.), a reduced nutritive 

 vacuole {«. v.), and two nuclei possessing very small central corpuscles. 



Fig. 4, — x 1000. The yolk bodies as seen in a preparation stained with 

 Bismarck brown followed by malachite green. Note the small refringcnt 

 structures contained in the yolk bodies (^. b.), and also their variety of form. 



Fig. 5. — X 1000. Portion of a section of a larva, type B, at the junction 

 of the larval cavity (/. c.) with the solid posterior end of the inner mass. In 

 addition to the flagellated cells {/I.e.), the cells with granular nuclei {c.ff.ti.) 

 and with vesicular nuclei (c. v. n.), there is also a group of small cells with 

 small nuclei {g.c). The cells with granular nuclei are flattened to form a 

 kind of lining to the larval cavity, and their nuclei are beginning to assume 

 an oval form. 



Fig. 5 a. — A portion from the centre of a section from the same larva as 

 Fig. 5. The groups of cells with small nuclei have more or less run together. 

 The yolk bodies in many cases present no change from that represented in 

 Fig. 1 ; others are greatly reduced in size and present a circular section instead 

 of an oval one, besides showing a certain amount of structure in the interior 

 and a tendency to stain red rather than blue, a state of things due to the older 



