162 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
laying of the next generation of eggs, which upon the theory of biennial spawning 
would be due in one year.* Through the courtesy of the United States Fish Com- 
mission this experiment was made in 1900-1901. On June 19, 1900, Mr. Vinal 
Edwards placed in a floating car thirty-six lobsters from which the old external eggs 
had been removed, fed them regularly, and on the first of each month following 
caught one of the animals and preserved its ovaries. When the last survivor was 
taken, May 1, 1901, just ten months and twelve days from the beginning of the 
experiment, not one of the animals had laid eggs. Further, an examination of 
the ovaries disclosed no evidence of absorption of the ova or abnormal retardation 
of their growth, such as we might look for upon the theory of annual spawning — 
nothing in fact but a slow, regular growth of the organs. 
2. 3. 
Fig. 1. — Initial stage of ovarian egg shortly after egg-laying in the lobster. Radius, 5.7 min.; contents, 0.77 
c. c. Animal taken 36 to 48 hours after egg-laying, July 29. 
Fig. 2. — Ovarian egg in intermediate stage, one year after egg-laying. Radius, 14.1 mm.; contents, 11.71 c. c.; 
average of ten ova from animal taken June 19, and ten ova. taken June 28. 
Fig. 3. — Ovarian egg in final stage, when ready to be laid. Radius, 32 mm.; contents, 136.97 c. c.; average 
of five unextruded ova from the oviduct of a lobster which had recently laid eggs, August 17. 
The testimony which is plainly borne by the structure of the ovaries of these 
animals is of much importance, and will be briefly analyzed. 
In a single generation of ovarian eggs three stages are entitled to special con- 
sideration: (1) The initial stage, when the ova of the preceding generation are laid; 
(2) the intermediate stage, when these eggs are hatched; and (3) the final stage, when 
the ovarian eggs have reached their full size and are ready to be expelled from the 
body. (Figs. 1-3. )f The time interval between stages 1 and 2 is known to be 
approximately one year, being measured by the development of the external eggs 
*Ibid, p. 72. 
fAll the figures in this paper are drawn to the same scale, with an enlargement of 40 diameters. Unless other- 
wise stated, the size of each egg figured represents an average of ten of the larger peripheral ova from the ovary of the 
same individual, all being subjected to the same treatment. The eggs were rolled under slips of glass and then outlined 
with the camera, the measurements being made from the sketches thus obtained. Several measurements of each egg 
were required, owing to the distortion which arises from mutual pressure in the ovary. 
