684 McAllister. — Nuclear Division in Tetraspora lubrica. 
divisions are here not essentially different from those in higher forms. In 
early prophase, apparently as the reticulum passes into a spireme, the 
chromatic material aggregates at one side of the nuclear cavity to form the 
synaptic knot. As it emerges from synapsis the chromatic material 
is in the form of a spireme thread. The nucleole retains its identity until 
about the time of the segmentation of the spireme to form the chromosomes. 
The further stages of mitosis are also in no essential way dissimilar to those 
of the higher plants. 
Dangeard’s work (9, 10) on certain of the Chlamydomonadaceae, while 
in no way complete or exhaustive in respect to any single species, has 
nevertheless shown that in this interesting group, regarded by many 
algologists as having the closest relationship with the Protozoans and 
even regarded as Protozoans by most zoologists, nuclear division does not 
vary essentially from that as established for the higher plants. 
Working on Chlamydomonas , Phacotus , Chlorogonium , Car ter ia , and 
Polytoma he has described and figured phases of the division of the nucleus 
in which a definite number of chromosomes arise from a reticulum. The 
spindle arises from the cytoplasm and lacks centrosomes. There is no 
f nucleo-centrosome ’ or equivalent body such as is reported by the same 
author, as well as others, for Euglena . Dangeard is of the opinion that the 
type of nuclear division in the Chlamydomonadaceae ( ; teleomitose ’) is of 
a higher type of development than that as determined for the Euglenidae 
(‘ haplomitose ’), — and he proposes this difference in nuclear division as 
a character by which to separate the former group from the latter. 
Davis in a discussion of spore formation in Derbesia (13) has given 
a few nuclear figures from the germinating spores. According to this brief 
reference, the spindle is intranuclear with minute granules at times to be 
seen at the poles. The spireme arises independently of the nucleole. 
Fairchild (17) is inclined to believe that in Valonia ) ‘ bei einigen Kernen’, 
centrosomes with faintly defined asters are to be identified. He says, 
however, — ‘ ich bin nicht sicher, ob mir wirklich Centrosomen vorlagen oder 
nur die convergirenden Enden der Spindelfasern, weil bei den ruhenden 
Kernen keine solchen Punkte zu finden waren.’ The spireme arises from 
the reticulum and the nucleole contributes no morphological elements to it. 
Debski (14) has shown that the nuclear division in Chara is more 
nearly similar in all its phases to mitosis in the higher plants than in any 
other Alga. The mode of spireme formation, the formation of the spindle 
and the cell plate seem almost identical with these processes in the nuclei of 
the higher plants. 
Golenkin (19) believes, from evidence obtained from Hydrodictyon and 
Sphaeroplea , that in the resting condition of the nuclei of these Algae the 
chromatin is accumulated in the nucleole. He regards nuclei of this type 
as primitive, probably occurring in the lower green Algae. 
