Observations 071 Notommata Werneekii. ByProf.Balbiani. 539 



My own observatioDS have led me to a difierent opinion to 

 that of either Huxley or Cohn. As I have already said, all the 

 individuals which passed under my notice during April and May 

 were females. I do not conclude from this the absolute absence 

 of males, as these may only appear in autumn. At the beginning 

 of my observations it was exclusively summer eggs which were 

 produced. Later on these eggs were mixed in increasing pro- 

 portion with winter eggs ; and finally, at the end of April and 

 the beginning of May, nearly all the eggs were of the latter 

 kind. Not only was the production of summer eggs very con- 

 siderably diminished, but a great number remained sterile, or if 

 an embryo was formed it died without hatching, even when it 

 had arrived at an advanced stage, as shown by the eye spot 

 visible through the envelope. These facts show the gradual 

 exhaustion of the vitality of the germ in the non-fecundated sum- 

 mer eggs. As to the winter eggs, I conclude that the assistance 

 of the male sex was not necessary to their production or develop- 

 ment, not merely from the fact that no male individual was ever 

 presented to my observation, but from the fact that seminal cor- 

 puscles were absent in the females extracted from capsules containing 

 winter eggs. A final proof of the absence of males is to be found 

 in the complete identity presented by all the summer eggs. We 

 know, by the researches of Dalrymple, Leydig, Cohn, Gosse, and 

 others, that the sex of the future embryo of the Eotatoria is 

 indicated in the egg, by various characters, such as form, size, and 

 colour, which difi'er in male and female eggs, but I have never 

 remarked this in the species under observation, whei-e all the 

 summer eggs resemble each other, even in the smallest details. 



Cohn * has raised the question whether the same female can 

 produce, either at the same or difierent epochs, summer and winter 

 eggs. He negatives it, claiming to have established that each 

 female only lays eggs of one kind. He even thinks that, when in 

 one species there are male eggs besides, the production of the 

 three sorts of eggs devolves on three difierent kinds of females. 

 My observations do not agree with the opinion of Cohn. N. We7'- 

 neckii enables the point to be easily decided, as the females enclose 

 themselves in separate capsules, in most of which 1 have found the 

 two sorts of eggs mixed in variable proportions, from which I con- 

 clude, contrary to the assertion of Cohn, that one and the same 

 female can produce the two sorts of eggs. The earlier layings of 

 the year are composed nearly exclusively of summer eggs, whilst it 

 is winter eggs which predominate in the latter. 



In spite of their name, the laying of the winter eggs sometimes 

 begins from the early spring. The name was founded on the fact 

 that the eggs pass through the winter and only hatch in the fol- 



* Lo<\ cit., p. 431. 



