- 2 - 



Technical remarks. 



It was at first very difficult to obtain good cuts through 

 the eggs, because of the presence of the great amount of 

 yolk which they contained. When embedded in paraffin 

 the yolk always crumbled away before the knife of the 

 microtome. 



The following is the method I usually used : — The 

 embryos were brought through successive degrees of alcohol 

 into absolute alcohol. Next they were left in celloidin 

 for some days. They were then taken from the celloidin 

 and put directly into chloroform. This has the double 

 effect of making the celloidin firm, and of rendering the 

 embryos ready to be transferred into paraffin. After 

 having been treated thus, the embryos were cut as ordi- 

 nary paraffin objects. The cuts were attached to the 

 object-glass with water; when all the cuts were arranged 

 on the glass, the water was quickly removed with a piece 

 of blotting - paper, whereupon very fluid celloidin was 

 poured over the cuts; they were then allowed to dry, but 

 being still enclosed in paraffin the cuts could not shrink 

 in any way. When quite dry the coating of celloidin 

 became very thin indeed. 



To remove the -paraffin I again always used chloroform. 

 Afterwards the cuts were treated in the usual manner. In 

 this way I managed to obtain several perfect series, the 

 yolk remaining in its place without being liable to crumble. 



The staining was always done with eosin and hsema- 

 toxylin, and invariably after cutting, the outer cuticle of 

 the embryos being impermeable to the reagents used. 



Literature. 



The object of this paper is to supply, as far as the 

 materials at my disposal permit, a gap in the literature 

 of the embryology of the Arachnids. Only three papers 

 have as yet appeared treating the development of the 

 Pedipalps. Of these one is on the development of the 

 Thelyphonidse, the other two treating the development of 

 the Phrynidse. Their titles are:— (1) Dr. Strubell (42), 



