THE MEIOTIC PHENOMENA IN BLAPS rig 
unite to form the X-complex, while the other chromosomes pair 
to form fifteen bivalents. In the first maturation mitosis the 
complex undergoes dissociation, four chromosomes—two large 
and the two small—passing to one cell, while the third large chro- 
mosome enters the other. The final result is the production of 
two kinds of spermatozoa, one with nineteen chromosomes, the 
other with only sixteen. 
A remarkable feature of the meiotic phase in Blaps is that the 
complex can be recognized in the spermatocytes at every stage, 
from the early synapsis to the metaphase of the first maturation 
division, owing to the fact that one of the large chromosomes 
appears condensed, like the so-called accessory or X-chromosome 
of other animals, while the other two large chromosomes persist 
in the form of long threads united with it. Furthermore, it has 
been possible to find that the latter do not pair at synapsis, but 
remain as separate individuals, a fact which led me (714) to the 
conclusion that telosynapsis takes place in this case, although 
the actual pairing of the other chromosomes was never observed. 
There are still several points which are left unsolved, since the 
material in my possession is not especially fit for their solution, 
but a comparative study of the conditions in other species of 
Blaps and the preparation of new material of B. lusitanica might 
give the clue to the phenomena described in the following pages. 
It gives me great pleasure to express my deep indebtedness to 
Prof. Edmund B. Wilson, to whom I owe sympathetic interest 
and valuable criticism throughout my work; also to Prof. Frank 
R. Lillie, Director of the Marine Biological Laboratory of Woods 
Hole, for the kind hospitality extended to me in that institution 
during the summer of 1918. Finally, and not the least, to the 
Junta para Ampliacién de Estudios e Investigaciones Cientificas 
of Madrid, for the fellowship granted, through which it has been 
possible to continue my studies in this country. 
