ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 127 



Triradiate Tapeworm from Horse.* — F. J. Meggitt describes a 

 triradiate abnormality in Anoplocephala perfoliata, previonsly noted by 

 Neumann. He shows how the disturbance of symmetry affects the 

 excretory, nervous, and reproductive systems. 



Leucochloridium macrostomum (Rud.) from Great! Grey Shrike.f 

 J, Ritchie, jun., records this Trematode for the first time in Britain. 

 He found it in the intestine of Lanius excuhitor, and probably in the 

 starling as well. 'The early stage is passed in the body of the snail 

 Succinea piitris. 



Control of Head Form and Frequency in Planaria.J — CM. Child, 

 continuing his studies on the dynamics of morphogenesis in experimental 

 reproduction, has experimented on the control of head-form and head- 

 frequency in planarians by means of potassium cyanide. The details of 

 each experiment are given in tabular form. In general, he found that 

 low concentrations of cyanide diminish head -frequency in pieces 

 representing the anterior third of the first zooid, have little effect on 

 the middle third, and increase frequency in the posterior third. Two 

 factors are chiefly concerned in determining whether a head shall 

 appear or not: 1. The reaction of the cells adjoining the cut surface; 

 2. The stimulation of the piece as a whole following section. The 

 effects of cyanide are due to its action on these two factors. All the 

 facts indicate that head-frequency varies directly with the metabolic 

 rate of the cells concerned in head-formation, and inversely as the 

 metaboUc rate of other parts of the piece. 



Kotatoria. 



Male-production in Hydatiua.§ — A. F. Shull and S. Ladoff, 



starting from the established fact that certain agents reduce the 

 number of male-producing females in Hydatina smta, have made 

 investigations with the two-fold aim (1) of explaining how the agents 

 prevent the appearance of the male-producing females ; and (2) of 

 discovering means of increasing male-producers. Their second line of 

 research proved the more fruitful. They found that the effect of 

 numerous substances in diminishing male-production is not due to 

 osmotic pressure, acidity, or alkalinity, or to the mere retarding of 

 certain processes. Very dilute solutions of calcium chloride repeatedly 

 increased male-production in one parthenogenetic line and not in 

 another. Magnesium chloride gave results that could not be inter- 

 preted, while potassium sulphate, iron chloride and ammonium chloride 

 all reduced male-production, as did also dilute bouillon. Oxygen in 

 the water increases male-production. Its effect is most marked in 



* Parasitology, viii. (1416) pp. 379-89 (1 pi. aud 2 figs.), 



t Glasgow Naturalist, viii. (1916) pp. 42-5. 



X Journ. Exper. Zool., xxi. (1916) pp. 101-26 (10 figs.). 



§ Journ. Exper. Zool., xxi. (1916) pp. 127-61 (1 fig.). 



