DEVELOPMENT OF CUCUMARIA ECHINATA 181 
The sections were stained with Heidenhain’s haema- 
toxylin and orange-G, and very satisfactory results were obtained 
even from the material which had been preserved for nearly 
twenty years, enabling pictures to be taken by photomicrography. 
For the reconstruction of sections, the graphical method with 
a glass-plate with parallel lines proved very simple and quite 
satisfactory. 
4, BREEDING SEASON. 
As mentioned above the late Professor Mitsukuri 
observed the spawning of Cucumaria echinataon July 21 
and 29, 1899, and on August 11, 1902, and Messrs. Aoki 
and Tsuchida seem to have observed it previous to June 18. 
I myself observed the same phenomenon on July 25 and 
August 1, 1916, but as stated above, on August 12, 1910, I was 
too late to secure the spawning individuals. 
Though the animal occurs in April and May ‘in such abun- 
dance that many boats dredge for them day after day, and by 
evening each one is loaded down with them’ (Mitsukuri, 81, 
p. 241), no spawning takes place in the evening, and an examina- 
tion of the gonads reveals the fact that they are still immature. 
It is strange that in July and August the animal does not occur 
in such abundance as in Apriland May. Further, from the latter 
part of July to the early part of August we meet with minute 
young provided with five to ten tentacles and pedicels of varying 
numbers, mingled with sand and broken shells, in which adult 
animals are found embedded. ‘These young measured only 
1-5—4:5 mm. in length on August 12-17, 1910, while on July 20-5, 
1916, they were remarkably large and in a far advanced state 
of development (see Table V). 
From these facts we may conclude that the breeding season 
begins about the middle of June and comes to an end in the 
early part of August, though it varies to some extent according 
to different years. The larger young found in the latter part 
of July may have developed from eggs spawned quite early in 
the season. 
Sex-Ratio.—Selenka (45, p. 157) noticed that in 
02 
