168 Mr Brindley, Notes on certain parasites, food, and capture 



well-marked dimorphism (Camb. Phil. Soc. Proc. xvii. part 4, 1914, 

 p. 831). 



The results summarised are as follows: 



Infection by Clepsydrina ovata. 



Thus the evidence so far obtained is that the dimorphism of 

 the forcipes in F. auricularia </ is not a result of or influenced by 

 gregarine infection — though in view of the well-established effects 

 of such parasitism on the secondary sexual characters of another 

 arthropod in Geoffrey Smith's case o^ Inachus dorsettensis modified 

 by the gregarine Aggregata {Mitt. Zool. Stat. Neap. xvii. 1905, 

 p. 406), the absence of positive evidence to the contrary at the 

 time Wheeler wrote, but now obtained, certainly afforded ground 

 for his support of Giard. 



In this connection I may quote a letter from Geoffrey Smith, 

 whose recent death at the battle front brings us into common 

 mourning with Oxford zoologists for a friend and colleague. 

 Writing to me about 1907 he said, " Have you noticed that Giard 

 attributes all cases of High and Low Dimorphism to parasitic 

 castration ? I am sure this is not right, but there is no doubt 

 that parasitic castration is a much more frequent occurrence than 

 is commonly supposed." These words, and a footnote to the same 

 effect in his paper " High and Low Dimorphism " (Mitt. Zool. Stat. 

 Neap. XVII. 1005, p. 321), are typical of the writer's insight and 

 balanced judgment. 



It may be stated that the gregarines in the Porthcressa earwigs 

 fell roughly into categories of small, medium, and large, but they 

 all seemed to be C. ovata. Rather more than half were small 

 individuals, and those of medium size were slightly in excess of the 

 large, but the sizes were not recorded in the case of the first few 

 earwigs examined. Very large numbers were found in syzygy, 

 and such associated individuals were of all three sizes. One 

 instance of syzygy of a large with quite a small individual was 

 observed. There was no noteworthy difference between the 



