6 
Psyche 
[March- June 
2. The cells of the corpora allata exhibit cytological evi- 
dence of secretory activity in the young larva — thus differing 
fundamentally from the corpus allatum component of the ring 
gland of the Brachycera which have been studied. 
3. The vacuolization of the cytoplasm of the corpus allatum 
cells at the time of puparium formation and pupation is com- 
parable to that found in the corpora cardiaca of Brachycera, 
and suggests that the gland is physiologically active at this time. 
4. The reduction in cytoplasm of the cells of the corpus 
allatum in the adult as compared with the larva is a further 
unique feature of Melophagus. 
5. The corpus cardiacum is a single median organ, not well 
developed in the larva of Melophagus , decreasing in the pupa 
and practically absent in the adult. While the reduction during 
development is characteristic of Brachycera, the extreme reduc- 
tion is unique among those insects which have been studied. 
The many unusual characters enumerated above correlate 
with the unusual reproductive habits of Melophagus , but it 
would be of little value to suggest the functional significance of 
the observations until some experimental procedures have been 
applied to this most interesting insect. The difficulties of breed- 
ing this species under controlled conditions in the laboratory 
has so far made such work impractical. 
Bibliography 
Burtt, R. T. 
1937. On the Corpora Allata of Dipterous Insects. Proc. Roy. Soc. B., 
124:13-22. 
Day, M. F. 
1943. The Homologies of the Ring gland of Diptera Brachycera. Ann. Ent. 
Soc. Amer., 36:1-10. 
Geitler, L. 
1940. Neue Untersuchungen iiber Bau und Wachstum des Zellkerns in 
Geweben. Naturwiss., 28:247-248. 
Hardenburg, J. D. 
1929. Beitrage zur Kenntnis der Pupiparen. Zool. Jarb. Anat., 50:497-570. 
Heymons, R. 
1895. Die Embryonalentwicklung von Dermapteren und Orthopteren. 136 
pp. Jena. 
Hoare, C. A. 
1923. An Experimental Study of the Sheep Trypanosome and its Transmis- 
sion by the Sheep Ked, Melophagus ovinus L. Parasit., 15:365-424. 
