126 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
early growth period. According to Stevens (:06*) and Nowlin (:06) 
in various Coleoptera the numbers of polar loops is at first the same 
as the somatic number of autosomes, but later one end of each loop 
becomes free, the free ends then uniting in pairs. 
On the other hand a side to side union of the chromosomes during 
synapsis has been described in mammals by von Winiwarter (:00, :02) 
and Schoenfeld (:01); in Amphibia by Janssens (:05), A. und K. E. 
Schreiner (:07); in fishes by Maréchal (:04), A. und K. E. Schreiner 
(:04, :05, :07); in insects by Otte (:06); in crustaceans by Lerat (:05); 
in gastropods by Bonnevie (:05, :06); in annelids by A. und K. E. 
Schreiner (:06, :06*); in worms by ‘Tretjakoff (:04) and Marcus (:06). 
The most detailed description of this type of conjugation has been 
given by A. und K. E. Schreiner (:04 to :07) in a series of papers on 
synapsis and maturation in various animals, in.an avowed attempt 
to find a common type of these phenomena which will apply to all 
organisms. ‘hese authors find that in all the forms studied the num- 
ber of polar loops is at first the same as the somatic number of chromo- 
somes and only later is the number reduced to one half the somatic 
number, the reduction being accomplished by two loops becoming 
parallel and gradually fusing. ‘They describe and figure the parallel 
approximation of the loops as taking place first near the pole where the 
loops are attached to the nuclear membrane, and gradually extending 
toward the opposite pole until the threads become connected through- 
out their entire length. The two components of the double thread 
thus formed then fuse into a single thread, which a little later splits 
along the line of fusion, so that the conjugants again become separated. 
The Schreiners find that the double thread is composed of a series of 
granules arranged in pairs, as I have described for the Orthoptera; 
but according to these authors one granule of each pair belongs to 
each conjugant, which means of course, that the chromosomes con- 
jugate granule by granule, as the Schreiners (:07, p. 470) clearly 
state. ‘Der Prozess, den wir die parallele Konjugation der Chro- 
mosomen nennen, ist demnach nicht als eine Konjugation der Chro- 
mosomen als Ganzindividuen, sondern als eine Konjugation der 
homologen Chromatineinheiten aufzufassen, und dieser Konjugations 
typus ist eben in der Zusammensetzung der Chromosomen aus ver- 
schiedenen Einheiten bedingt.” ° 
I have already described at length my reasons for believing that such 
a method of conjugation does not occur in the Orthoptera, although 
Otte (:06) has described it for Locusta. I have occasionally seen the 
spireme threads lying parallel to each other in pairs near the distal 
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