1918] BUCHHOLZ—PINUS 187 
being of vegetative origin. He described a “‘nest of cells” from 
which individual cells elongate, and thought that the embryonal 
tip cell was cut off some time after elongation. 
SCHACHT (35) agreed with SCHLEIDEN that the pollen tube 
enters the corpusculum and produces the embryo at its base. 
He described the rosette correctly as consisting of 4 cells instead 
of the 5 shown by Mrrpet and Spacu. ScuHacut described the 4 
tiers of 4 cells each, known to us as the end product of the pro- 
embryo stage. He announced definitely that the 4 rows of cells 
in Pinus Pumilio always separate into 4 embryos and believed 
that they would split up further. In Taxus baccata and Abies he 
reported no splitting of the product of the corpusculum into several 
embryos. 
GOTTSCHE (14) gives a critical review and confirmation of the 
facts known at the time and a more accurate description of the 
corpusculum, which he found to originate in some unpollinated 
cycads, and is therefore independent of the pollen. 
HOFMEISTER (17) made a careful study of all stages in the 
development of the ovule and confirmed the facts then known. 
He pointed out how wonderfully simultaneous fertilization occurs 
in all the plants of the same species and how rapidly the pro- 
embryo stages are passed through. He was the first to regard 
the terminal cell of the early embryo as an apical cell. He thought 
also that the later embryo and seedling grow by means of an apical 
cell, and even believed he could demonstrate it in the adult stem 
tip of conifers. 
PFITZER (32) denied the existence of an apical cell in the stem 
tip of conifers, but confirmed HorMEIsTER’s work in regard to the 
existence of an apical cell in the early embryo, although he assigned 
to it only about 5 segments as a maximum for Thuja, and in 
Pinaceae he stated that the apical cell stage was even shorter. He 
calls attention in his conclusion to the fact that this may be taken 
as a case of embryonic recapitulation of the pteridophyte manner 
of development. He published no figures. 
STRASBURGER (38) made a very careful study of the embry- 
ogeny of 8 or more genera of gymnosperms. In many particulars 
he corroborated the former accounts. His many excellent figures 
