LITERATURE ON CYCLOPS 709 



has been freed from all visible animal life; a small piece of green 

 vegetable matter, such as a blade of grass or the leaf of a water plant, 



is placed in the vessel to provide food, after having 



, r 11 u j T t Life History 



been carefully washed. In a few days, sooner or later 



according to the temperature, the eggs hatch out, and the larvae can be 

 seen as minute white specks floating about in the water. The young 

 larva is termed a ' naupilus '. It consists of an oval body with three 

 pairs of appendages, the posterior two of which are biramose, and 

 probably represent the mandibles and maxillae, the anterior pair repre- 

 senting the antennules. They are all used as organs of locomotion. 

 The alimentary tract is easily visible through the transparent integument, 

 and may be seen pulsating in the fresh condition. The larva moults 

 at least twice, and after each change several buds appear, which later 

 on become the legs. 



Graham, in his work on the Cyclopodae of the African Gold Coast, 

 points out that in any one neighbourhood there are a large number of 



different species of Cyclops, the habits of which vary 



, r i i -i 11- , Bionomics of Cyclops 



some are surface feeders, while others only live at the 



bottom. Many of the species are found only in foul water, while others 

 can only live in fresh water. Quite a number of the species have the 

 habit of climbing up stalks of water-weeds, surrounded by a drop of water 

 which they carry with them ; some never leave the water. Lastly, there 

 are some species which only occur in streams, and are never found in 

 ponds or wells. On the Gold Coast Graham noted that certain species 

 appear at particular times of the year and that there is quite a marked 

 difference in the seasonal prevalence. It should also be remembered 

 that a number of species of Cyclops have their natural nematode parasites 

 which have nothing to do with the Guinea-worm. 



In conducting any experiments with Guinea- worm and Cyclops nega- 

 tive results may be entirely due to a choice of an unsuitable species, 

 and it is therefore very important to study the different species, their 

 geographical distribution, seasonal prevalence and habits. 



LITERATURE 



BRADY, G. S. Notes on Dr. Graham's collection of Cyclopodae from 



the African Gold Coast. Annals of Tropical Medi- 

 cine, Vol. i, No. 3, 1907. On some species of Cyclops 

 and other Entomostraca collected by Dr. J. M. Dalziel 

 in Northern Nigeria. Ibid., Vol. iv, No. 2, 1910. 

 The above papers contain descriptions of several 

 species of Cyclops and are useful for a systematic 

 study. 



