1893.] MICROSCOPICAL JOURNAL. 347 



Both sexual elements may be found in the same individual 

 sponge, but even in hermaphrodites either the male or the 

 female element is in excess of the other ; in some species the 

 sexes are quite distinct. The ova developed from Archseocytes 

 or wandering amceboid cells, which increase in size and acquire 

 a store of reserve nourishment in the form of yoke granules. 

 At first they exhibit amoeboid movements, but as they increase 

 in size they come to a resting stage. In Easpongia officinalis the 

 ova occur congregated in groups within the mesoderm, thus 

 presenting an early form of ovary. 



A New Sub-Stage. 



By GEO. WHITFIELD BROWN JR. 



NEW YORK. 



It was about B. C. 977 that "The Preacher" asked, "Is there 

 anything whereof it may be said, See, this is new?" (Eccl. I, 

 10). Novelty has so of en been honestly though mistakenly 

 claimed, that I hesitated about the adjective in the above cap- 

 tion ; but, if forgotten b}' the reader, I feel that he should be 

 willing to be reminded of a good thing. And I am quite sure 

 this sub-stage is a good thing for I have had one in continual 

 use for nearh'^ a year now, and sj^eak only whereof I know. 

 The sub- stage is scarcely second in importance to the stage it- 

 self of any first-class instrument, in the judgment of Dr. Dall- 

 inger (Carpenter, p. 169), and an efficient and economical one 

 is certainly a great desideratum with any worker. 



The one now described and illustrated is fully shown actual 

 size in the accompan3ang drawing, partly perspective and partly 

 sectional, and its construction and operation can be therefrom 

 easily ascertained, aided by a few words of explanation. It was 

 made for me by Zentmayer of Philadelphia according to my 

 specifications and has given perfect satisfaction. In Fig. 1 the 

 bracket L, sliding on the tail-piece or moved by rack and pinion, 

 is the usual support of a sub-stage properly so called. The sub- 

 stage itself is secured thereon by a centering set-screw J, and 

 consists substantia,lly of a double elbow with two arms, A and 

 B, each carrying a similar tul)ular holder for receiving accessory 

 apparatus, the former from above and the latter from below. 

 In the space between the upper and lower holders is situated a 



