90 Bashford Dean Memorial Volume 



plates II, III and IV inclusive). In fact, the large eggs are approximately seg- 

 mentally distributed, one egg for each segment in the muscle of the abdominal wall or in 

 the mesonephros. If the arteries in the mesovarium of a female which contains large eggs 

 are examined, especially in an individual whose arteries have been injected with a color 

 mass, they also will be found to be approximately segmental, one ovarian artery to each 

 muscle segment. Dean made one drawing to illustrate the ovarian arteries in a female 

 whose arteries had been injected with a red mass. Figure 12, plate III. The ovarian 

 arteries are also shown in Figures 13 — 16, drawn from specimens whose arteries were 

 not injected. Each ovarian artery arises directly from the aorta, extends downward 

 between the two layers of the mesentery to the line of attachment of the mesovarium then 

 continues between the two layers of the latter to within a short distance of the ovary and 

 there divides into two or more branches. Some of the smaller branches supply the smaller 

 eggs, while the larger branches go to the large eggs and spread out upon the surfaces of the 

 ovarian capsule by means of further branching. Microscopic examination reveals that the 

 arteries and their branches are contained within the connective tissue sheath of the capsule. 



The approximate segmental distribution of the large eggs is probably determined 

 by the location of the ovarian arteries, and the eggs favored with a direct stream of arterial 

 blood through these arteries doubtless outstrip their neighbors in the accumulation of 

 yolk material. Usually each large egg is supplied with blood by a single ovarian artery; 

 and there is a corresponding ovarian vein for each egg. Each ovarian artery increases in 

 si2;e as its corresponding egg grows larger. After the mature eggs have been extruded 

 from the body, the ovarian vessels remain large for a time, then gradually become smaller 

 coincidentally with the decrease in si2;e of the corpora lutea. The blood in the ovarian 

 vessels is undoubtedly involved in the processes of resorption of the corpora lutea; it is 

 possible, therefore, that other eggs do not receive a sufficiently large supply of blood to 

 commence growing until the corpora lutea are almost or completely resorbed. Nothing is 

 known regarding the factors which control the entire series of events concerned in the 

 development of the eggs. Also the time required for the larger eggs to grow to the size 

 and condition of maturity is unknown : Dean (1899) expressed the opinion that it is one year. 



FATE OF THE EGGS WHICH DO NOT DEVELOP TO MATURITY 



In the ovary of every female specimen of Myxine and Bdellostoma are very many eggs 

 which are smaller than 2 to 5 mm. in length. These small eggs are so numerous that prob- 

 ably many of them do not develop to the mature condition. When the mesovarium of an 

 adult female is examined closely, small brown nodules can be seen scattered throughout the 

 ovary, usually toward the inner, or attached margin of the mesovarium. I observed these 

 structures (Conel, 1917, P- 124) in adult females of Myxine, called them "brown bodies," 

 and briefly described them. I interpreted them as degenerate eggs and corpora lutea 

 which had been almost entirely resorbed. Very probably these brown bodies do repre- 

 sent the remains of those small eggs which are less favored than their neighbors as to 



