Miscellaneous. 159 



ripe egg by means of hot water, it appears to be covered with small 

 rounded areas, which are possibly the impressions of the follicular 

 cells. No distinct pores could te detected in it, but when wrinkled 

 it appears to be vertically striated, which may argue in favour of 

 their presence. 



For some time before oviposition the plcopods appear to be filled 

 with a milky-white substance. This appearance is caused by the 

 distended condition of the cement-glands, to the activity of which 

 the secretion which forms the secondary egg-membrane is due. If 

 the cuticle is removed from a pleopod at this time the tissue is seen 

 to be studded with very minute, round, whitish bodies — the cement- 

 glands. They are most abundant over the posteriorly directed sides 

 of the laminae, and extend up into the stalk. It is noticed also, in a 

 lobster " in berry," that it is upon this side of the swimmeret that 

 the eggs are mostly attached. I have found the glands in the five 

 anterior pairs of plcopods only ; but it is possible that they may 

 occur in the telson, the uropods, and epimeral regions. The glands 

 occur singly or in clusters, and are closely crowded along the thick- 

 ened edges of the laminae. 



Sections show that the gland is composed of a very delicate sheath 

 of connective tissue arid a simple ei3ithelium consisting of tall pyra- 

 midal cells. The polygonal base of each cell occupies the periphery, 

 at which a large round nucleus is situated, and the apices of the 

 cells meet near the centie of the gland, the lumen of the organ 

 being at this time very slight. It is almost impossible to detect in 

 sections the opening of the gland to the exterior, but it is quite 

 probable that each gland opens separately, Cano describes these 

 glands in numerous forms as bottle-shaped structures, the necks or 

 ducts of which open to the exterior through pores in the cuticle. 

 Pores can be shown to exist in the lamina of the pleopod by re- 

 moving the tissue by caustic ])otash and distending the cuticle with 

 water; but pores of the same kind also exist in the appendages of 

 the male, where no cement-glands occur. I cannot at present say 

 how the pores are distributed on the surface of the cuticle, but it is 

 probable that they are not confined to any particular area. 



If the glands are examined shortly after oviposition, they show a 

 remarkable change in structure. The glands are enlarged and the 

 epithelial cells have the appearance of degeneration, their nuclei 

 presenting every stage of fragmentation, from the condition of minute 

 chromalin-particles, which fill almost the entire gland, to deeply 

 stained round granular masses, which are much larger than ordinary 

 nuclei. Under these conditions cell-outlines are very dim and the 

 lumen of the gland is not open. 



It stems quite probal^lc that the peculiar gland-like structures 

 which I have described in the immature ovary of the lobster (see 

 these Circulars, no. 88) are concerned with the growth of the 

 ovarian eggs. Numerous follicular cells enter these growing ova at 

 an early stage, and gradually become converted into food-products. 

 Their nuclei break up into very small vesicles, and finally lose all 



