46 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
The majority of the nerve-cells of Insects are pyriform, unipolar, 
and send out a prolongation of regular calibre, whence there are given 
off laterally fine branches which ramify. The primitive prolongation of 
large cells, which may be followed in a certain number of cases, is con- 
verted into the peripheral nerves or the connectives. 
An abdominal Insect-ganglion consists of two ventral columns and a 
ventral lobule, formed of a very dense and a very fine fibrillar substance, 
and a dorsal lobule formed of a fibrillar coarser substance, which is 
traversed by three groups of dorsal connectives. The abdominal nerve 
has three roots, one of which is dorsal. A thoracic ganglion differs 
only in the addition laterally of two crural lobes. The crural nerve is 
composed of two kinds of fibres — some very fine, which blacken with 
osmic acid, and thicker fibres which stain with borax-carmine ; the former 
pass into the ventral part of the ganglion, and the latter into the dorsal. 
Details are given as to various nerves, and to the special parts of par- 
ticular Insects. 
Physiological experiments confirm the anatomical demonstration, and 
show that the ventral lobe of the ganglion is sensitive, and the dorsal 
motor. 
The movements of Insects are due to an unequal stimulation of the 
legs of the two sides of the body, and this awakens by fundamental 
association the motor mechanism. 
Early Stages in Spermatogenesis of Insects.* — Prof. N. Cholod- 
kovsky urges that there can be no doubt that the presence of one or 
more large spermatogonia is a very common phenomenon in the spermato- 
genesis of Insects. As he has always been able to see nuclear- division 
figures in these large cells he cannot accept the view of Nogakushi that 
they are merely supporting cells, analogous to the rachis of Nematodes. 
He would rather compare them to the contents of the terminal chamber 
of the ovarial tube, especially as Nogakushi has himself shown that the 
large cell is found not only in the testicle, but also in the ovary of 
the caterpillar. 
Antennary Organ of Insects. | — Mr. C. M. Child describes “ John- 
ston’s organ,” a sensory organ lying in the second antennary joint of 
many insects. It consists essentially of ganglion-cells which are con- 
tinued into long rod-like processes, or are connected with “ rods ” by 
means of fibres. The rods end in pores in the membrane between the 
second and third joint or on chitinous processes of the margin. In the 
males of Culicidse and Chironomidae the organ is very large. It arises in 
the larvae of these orders as an annular fold near the base of the 
invaginate hypodermic antennary saccule. The rods usually arise from 
the coalescence of cells. The function of the organ seems to be primarily 
tactile, ^secondarily to respond to vibrations, and in the above-mentioned 
males to hear the sound which the females make. 
Classification of Lepidoptera.if — Mr. G. F. Hampson calls attention 
to recent contributions to the classification of the Lepidoptera by 
* Zool. Anzeig., xvii. (1894) pp. 302-4. 
t Zeitschr. f. wiss. Zool., lviii. (1894) pp. 475-528 (2 pis.), 
t Ann. and Mag. Nat. Hist., xiv. (1894) pp. 254-61. 
