INVERTEBRATAj CRYPTOGAMIA, MICROSCOPY, ETC. 



63 



into a nucleated body (Hp) which, although not separated from the 

 cylinder by a cuticular membrane, seems to answer to a cell of the 

 vitreous body (^gl). The comparison — interesting as illustrating the 

 fundamental similarity of sense organs — is illustrated by the woodcut 

 reproduced. The paper is moreover accompanied by three plates. 



Fig. 8. 



A, diagram of a visual segment o{ Buthus ; B, diagram of an a(?bustic segment 

 of Acridium. aCu, outer cuticle; Up, hypoderm ; gl, vitreous body; icu, inner 

 cuticle; r^, distal nucleus'; s^, crystalline rod ; m'., middle nucleus; o', axial 

 cord ; gz, nerve-cull ; n, optic or auditory nerve. 



a- Insecta- 



Blastoderm and Yolk-balls in Insects.* — In a paper on this 

 subject Dr. Alexander Brandt of St. Petersburg comes to the follow- 

 ing conclusions : — - 



The yolk-balls (Dotterballen) of insects are not the morpholo- 

 gical equivalents of cells, but are elements of a higher order. They 

 do not originate in a diffusion (Zerfliesseu odor Aufgohcn), through 

 the yolk, of the protoplasm of the intravitelline germ-cells, or, to put 

 it in another wnj, by a depositicjn (Eiulagerung) of yolk-substance 

 in the protoplasm of these intravitelline cells, but by the accretion 

 (Umlagcrung) of yolk-spherules around tliem. The yolk-balls are, 

 therefore, like the egg itself, and unliko the germ-cells, not primary 

 cells (cellula) primariaj s. cyta), but secondary cells (cellulaa sccund- 

 ariae s, metacyta). 



Correlation of Mutilation in the Larva with Deformity in the 

 ImagO.t — M. Mcliso has operated upon ton selected silkworms by 

 cutting off the right metathoracic leg of each. All went through their 



• ' Aich. Mikr. Auat.,' xvii. (1879) p. 13. 



t 'ConiptcH Kcudus 8oc. Entomol. Belg.,' 1879; bOe ' Proc. Eutomol. See. 

 l.on'loD,' l.'^7y, p. x.\.\ii. 



