292 BUI^IvETIN OP THE BUREAU OP FISHERIES. 



the periphery, where the epithelium has become decidedly glandular in appearance. 

 (Fig. 4, pi. xtv.) These gland-like organs apparently contribute to the growth of 

 peripheral eggs for a short period and subsequently disappear. Amoeboid cells pass 

 from them into the eggs, where their nuclei degenerate, giving rise to swarms of fine 

 chromatin-like granules, which persist for a considerable time. In 5 weeks from the 

 date of oviposition the gland-like bodies are reduced to shrivelled remnants, of which 

 later no vestige can be recognized. 



WhUe the massive yolk of the eggs is mainly derived from materials drawn from the 

 blood and laid down at first in the cytoplasmic reticulum, the migratory cells just 

 described contribute in a minor degree toward the supply, and the glandular follicles 

 possibly manufacture yolk directly, although the evidence which seems to support this 

 idea may be wholly deceptive, owing to the presence of degenerative elements. 



In the course of 5 or 6 weeks the ovary, flecked with degenerating eggs which failed 

 of passage and now of a bright orange color, begins to assume a light-green tint. Exami- 

 nation of the larger ova shows that the pigment, a green lipochromogen, is first formed 

 in the yolk spheres immediately around the nucleus and thence spreads centrifugally 

 until it involves the entire yolk mass. In a year's time, or at the beginning of the 

 summer following ovulation, the peripheral eggs, while but little larger, are more uni- 

 form in size and color, and the whole organ presents a characteristic pea-green tint. A 

 second period of active growth ensues, followed by a second interval of quiescence during 

 the winter. At the beginning of the third summer after the last ovulation these eggs 

 enter upon their third and last period of active growth and are soon ready for extrusion. 

 (Fig. 5, pi. XLv.) 



Owing partly to the presence of the egg membrane or chorion, absorption of the 

 residual eggs at each period of laying is exceedingly slow. After the lapse of 2 years 

 traces of them can be detected, and the presence of these orange flecks in the ovary of 

 any lobster tells us conclusively and at a glance that it has already spawned once at 

 least. 



The ripe eggs, as spawning time approaches, lie free in the lumen of the ovary, 

 which they distend to an unusual size, its elastic walls becoming very thin in consequence. 

 Maturation may be completed in the ovary itself, but fertilization is possible only after 

 the eggs have been expelled from the body. The massive yolk is inclosed in a flexible 

 and transparent shell or chorion, secreted, as we have seen, by the egg follicle or sac, 

 and by the time the ovum has reached the ducts its nucleus (female pronucleus') has 

 migrated to the surface. The ripe egg possesses a single membrane only. 



DISTURBANCES IN CYCUCAL CHANGES OF THE OVARY. 



It is convenient to notice here what the fishmonger in England sometimes calls 

 "black lobsters." During the summer months the English lobster dealer is said to 

 examine his stock daily and to cull for immediate sale such animals as show a tendency 

 to blacken. It seems that whenever females with ripe ovaries happen to be caught 

 and are either sent to market or kept in floating cars, the normal reflexes which attend 



