HARD WICKE'S SCIENCE-GOSSIP. 



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lobes accompany them. A 

 occur at the other extremity. 



few yet smaller lobes 

 (Fig. 53-) 



Second Day. October 16th. 1 1.30 A.M.— The yolk 

 has retreated equally from all parts and is surrounded 

 by a granular protoplasmic layer. The thickness of 

 the egg-shell is distinctly visible. In the majority of 

 the specimens the yolk is equally granular throughout 

 (Fig. 54), but in others upon the same slide the 

 granules have collected together forming apparently 

 hollow spheres. 



2 P.M. — The protoplasmic layer has broken up into 

 numerous small divisions (cells). An outer layer of 

 cells is at first visible, but later in the day the whole 





F"g- 55- 



Fig. 56. 



layer forms two layers. The yolk contains numerous 

 yolk spheres. 



10 P.M. — The position of the yolk has altered con- 

 siderably. In profile the yolk still occupies a nearly 

 central position, but looking down upon the egg, it is 

 seen to extend to each side. It stops before it reaches 

 the posterior extremity, being produced further at the 

 sides than in the centre, the posterior of the embryo 

 being formed of granular protoplasm and not quite 

 extending to the shell. Anteriorly the yolk tapers to 

 a neck which does not extend to the shell, but is 

 surrounded by granular protoplasm. (Fig. 55.) 



Third Day. October ijth. 9.30 A.M. — Viewed in 

 profile the commencement of the segments is faintly 



indicated at the upper surface. The yolk extends to 

 the anterior upper surface and is nearly separated 

 into two portions by a bite, which occurs on the 

 upper surface a short distance from the anterior. 

 Looking down upon the egg, the only noticeable 

 change is the paleness of the neck at that portion 

 where the bite occurs. 



6.30 P.M. — This bite in the neck of the yolk pre- 

 ceded the formation of the head-fold, noticeable on 

 my next observation. An indentation at the posterior 

 extremity represents the commencement of the hindt 

 gut, while a similar indentation beneath the head-fold 

 that of the fore gut. 



Fourth Day. October i&th. 9.45 A.M.— The fore- 

 gut and the hind-gut are both apparent, they are 

 lined by a layer of cells. The yolk is more con- 

 centrated, lying between these embryonic organs, 

 and the mid gut is formed within its upper portion. 

 The appendages of the head now appear as. bulging 

 processes. 



10 p.m. — The segments do not appear completed, 

 they are not apparent on the surface against the lower 

 surface of the shell. The fore and hind guts extend 

 to the mid-gut, both anterior and posterior limbs are 



Fig- 57- 



represented by corresponding processes as also the 

 papillce of the terminal segment. (Fig. 56.) 



Fifth Day. October 19th. 2 p.m.— The larva has 

 now attained the complementary number and form 

 of the limbs and head appendages. All that is 

 necessary previous to its escape, is that its body 

 should increase in size and the internal viscera be 

 more fully developed. (Fig. 57.) 



Growth from this period until its escape is apparent 

 in the body only, which becomes bent upon itself. 

 Besides the occasional movements observed as it 

 adjusts its increasing length to the cramped habita- 

 tion, the claws of the anterior limbs are, at certain 

 periods, expanded and retracted several times, and 

 often simultaneously the larva scrapes with its 

 mandibles against the shell. These movements may 

 be simply to effect a more comfortable position— 

 although apparently with another purpose— Aft, to 

 aid its escape. Before its escape I observed that the 

 alimentary canal, the nervous and the circulatory 

 systems were complete. The shell as frequently 

 bursts at one point as at another. All the larvre were 

 liberated on the evening of the 19th. 

 ( To be continued. ) 



