PSYCHE 
Vol. L March-June, 1943 Nos. 1-2 
THE CORPUS ALLATUM OF THE SHEEP KED, 
MELOPHAGUS OVINUS L. 
By M. F. Day 
Washington University, St. Louis, Mo. 
It has recently been shown (Thomsen, 1941; Day, 1943) 
that the condition of the corpus allatum and corpus cardiacum 
in muscoid flies is highly specialized when compared with other 
insects, since these glands have fused to form the so-called 
Weismann’s Ring or ring gland. Burtt (1937) has found that 
this condition is not found in the Nematocera which he studied, 
for a typical paired corpus allatum was present in the larva of 
species of Chironomus and Tipula. However, Burtt considered 
the corpus cardiacum to represent the oesophageal ganglion. 
In view of the interesting physiological effects of the ring 
gland on the ovaries reported by Thomsen (1940), the con- 
dition of the corpora allata and cardiaca in Melophagus presents 
a particularly interesting problem, for in this insect viviparity 
is highly developed. No observations on these glands in Melo- 
phagus are to be found in the literature, except those embryo- 
logical studies of Pratt (1901) referred to below. Other ana- 
tomical studies include those of Hoare (1923) and Hardenburg 
(1929). 
The following notes on the corpora allata and cardiaca of 
Melophagus are presented here as one of a series of investiga- 
tions of these glands in the Order Diptera. Conclusions regard- 
ing the homologies of the structures described are based upon 
morphological and comparative histological evidence. 
The techniques employed have been described previously 
(Day, 1943). 
