OF THE INVERTEBRATE ANIMALS. 23 



numerous globules (vesicles of fat) which were insoluble in pot- 

 ash and acetic acid, as also other molecules (albuminates) so- 

 luble in these media, but no other solid particles ; when incine- 

 rated, it left a considerable quantity of phosphate of Hme (by 

 approximative determination 8 per cent.) with a little alkaline 

 phosphate and carbonate of lime, which did not pre-exist as such. 

 This phosphate of lime existed in it in a state of solution, for 

 ammonia rendered the mass, placed under the microscope, very 

 turbid. In fourteen to sixteen hours the soluble molecules 

 (albuminate, perhaps also phosphate of lime) had accumulated 

 around the fatty vesicles forming globular masses ; some of these 

 globular masses were already surrounded by a membrane, others 

 not; at the same time it contained numerous rhombohedric 

 crystals (of carbonate of lime) which effervesced with acids. 

 When treated with potash, the primary cells, as also their gra- 

 nular contents (albuminates?), swelled considerably, became 

 transparent and dissolved ; in each the fat globule appeared as a 

 nucleus; hence they were not yet composed of chitine, unless per- 

 haps this, in its early and perfected condition, preserves relations 

 similar to those of gum to cellular membrane, i. e. is soluble. 

 Lastly, in from twenty-four to thirty-six hours, several of these 

 primary cells were found lying beneath the same elements ; they 

 were spindle-shaped and elongated, still swelled in potash, but 

 did not now dissolve; they appeared therefore to consist of chitine. 

 I was not able to trace the process any further, as the animals 

 died from want of attention, and it was too late in the year to 

 procure others. 



We thus found a considerable quantity of phosphate of Ume 

 in a state of solution in the cytoblastema, also some lime in or- 

 ganic combination (probably with albumen as albuminate of 

 lime). I shall return to the import of these facts in the consi- 

 deration of the MoUusca. 



Finally, two other membranes, which run beneath the tegu- 

 ment, belong to the cutaneous system of the Craw-fish ; their 

 basis consists of the same substance, viz. chitine. The external 

 one covers the whole tegument internally, of which it forms the 

 matrix, as the dura mater does the cranial bones. It is covered 

 on both sides with a layer of dai'k roundish epithelial cells, con- 

 taining a sharply-defined, dark, granulated nucleus ; these con- 

 sist of a protcine compound (are dissolved by potash). Its tex- 

 ' turc is made up of numerous intimately interwoven longitudinal 



