Igt5] HUTCHINSON—ABIES BALSAMEA 407 
Ascomycetes. ‘‘The time and degree of the combination of the 
sexual chromosomes is a variable matter. If the prochromosomes 
can remain in one nucleus with the double chromosome number, 
or in two distinct nuclei through part or all of the sporophyte 
generation, it is also possible that they may combine in one nucleus 
into bivalent chromosomes, and maintain their identity in this 
» 
a AY 1s 
Alix 
Diagram A.—An interpretation of fertilization in some animals and in Pinus, 
according to the accounts heretofore recorded 
Diagram B.—An interpretation of the phenomena already described: the chro- 
matin originating from the egg nucleus is shown in solid black, that from the male 
nucleus is outlined and barred; the argument upon which such an interpretation is 
based is included in the description given in the text; the facts of spindle formation 
are re: mass 
ee ee 
Diagra from Grécorre’s (7) “‘schéma de linterprétation meta- 
syndetique ase thevades chia,” as found in certain lower animals; compare fig. B. 
condition through the sporophyte generation until a true reduction 
occurs in spore formation.’ In the well known case of Cyclops, 
studied by Harcker, the parental chromosomes do not mingle, but 
persist as individuals and maintain their separation-into two groups 
through several cell generations after ‘‘fertilization.” We may 
consider the union of egg and sperm as consisting of three stages: 
(1) the two nuclei enter the same cytoplasmic mass; (2) the two 
