SCIENTIFIC NOTES. 173 



that has been written on the subject, and so have had to rely entirely 

 on my own personal observations. — W. Farren, Cambridge. 



Fecundity of Spilosoma lubricipeda. — It occurred to me lately 

 that it might be interesting to ascertain whether, in the event of a male 

 or female being induced to pair a second time, the number of fertile 

 or fertilised ova could be thereby increased. Having no bred speci- 

 mens ready, I selected several pairs of the prolific 6". lubricipeda, which 

 were just then emerging in great numbers. For distinction I shall 

 call the males m i, m 2, etc., and the females f i, f 2, etc. 



I took m I and f i in cop., and boxed them in (what I shall call) 

 box I. Boxing them, unfortunately, made them separate, but in due 

 course about i8o ova were deposited. After this, they again came 

 together, and as a result fi laid about 100 more ova. I then re- 

 moved them from box i, and placed m i in box 2 with another 

 female, f 2, and f 1 in box 3 with another male, m 2 ; mi and f 2 

 soon came together, and as a consequence f 2 in due time deposited 

 about 440 ova. On the other hand, m 2 and f i at first took no 

 notice of each other, the reason being that f i was still engaged in 

 oviposition, which lasted until about 100 more ova were laid. But 

 after this I found m2 and fi in cop., and as a result (apparently) 

 about 140 more ova were deposited by f i, making up the enormous 

 total of 520 ova laid by one female, while m i was (apparently) 

 responsible for the deposit of more than 800 ova. 



Having been so far successful, I tried a different experiment. I 

 placed another male, m 3, and another female, f 3, together in box 4, 

 and in due course about 400 ova were deposited. I then removed 

 them, together with another female, f 4, into box 5. About sixty more 

 ova were laid in this box, which, from their position I attributed to 

 f3. I then removed m3 and f4 to another box, where thirty ova 

 were deposited ; but, unfortunately, nothing more came of it, as all 

 the moths died soon after. 



Now as regards fertility. Only about one-half of the 180 ova first 

 laid by f I hatched out, whereas about two-thirds of the remainder 

 proved to be fertile. In other words, about three-fifths of the whole, 

 or scarcely more than 300 ova had been fertilised. On the other 

 hand, virtually the whole brood deposited by f 2 proved fertile, less 

 than ten having failed to produce larvffi. x^ssuming, then, that m i 

 was responsible for about 220 of the fertile ova laid by f i, and for 

 430 of those laid by f 2, m 2 must have fertilised no less than 650 

 ova. Nearly all the ova deposited by f 3 hatched out, making about 

 450 fertile ova ; that is, of course, on the assumption that the sixty 

 ova deposited in box 5 were laid by f 3. I think this may be taken 

 as about the maximum of fertile ova deposited by one female of this 

 species. So far as I am able to judge from the above experiments, 

 I should incline to the opinion that a second pairing does not in- 

 crease the number q[ fertile ova deposited by one female; but, that 

 it does, or may, increase the number of ova fertilised by one male. 1 

 may just add that the above are only a few of the experiments which 

 I tried, but which, for various reasons, led to no result of general 

 interest. Many species decline to pair a second time. — George 

 HoLLis. July, 1892. 



The Ova State of Geometr^e. — The following few rough notes 



