homologous Alternation of Generations in Plants . 351 
change of form : this latter view has however found acceptance 
with more than one writer: Strasburger 1 and Pringsheim 2 
both contemplated the possibility of the sporophyte having 
originated as a modification of a gametophyte : thus Stras- 
burger wrote as follows 3 : ‘For all plants from the Mosses up- 
wards it appears to me probable that we have to do merely 
with a differentiation of a single original generation, that is 
with a Strophogenesis, and that if a developmental cycle 
consists of more than one independent, living, i. e. physio- 
logical, individual (according to Haeckel’s definition), these 
individuals owe their origin only to individualisation of 
certain members of a single generation ’ ; while Pringsheim 
wrote 4 : ‘ The alternation of generations of the Mosses 
appears accordingly as a contracted form of the alternation 
of generations of the Thallophytes, in which the neutral 
generations are reduced to one, and this one remains in 
inseparable connection with the sexual. — The great apparent 
difference in habit of the Moss sporogonium and the Moss 
plant thus reduces itself to the feeble development of the 
vegetative part, i. e. the axis, which is connected with the 
early formation of the sporangium upon it. — In the true 
Mosses in which the axis (of the sporangium) is less feebly 
developed than in the Liverworts, the identity between it 
and the Moss stem is expressed even in the anatomical 
structure.’ This identity Professor Pringsheim considers to 
be demonstrated by the production of protonemal filaments 
from the seta itself (apospory), and he suggests it as not 
improbable that teratological conditions of the Moss sporo- 
gonium may be found bearing rudimentary leaves. Here 
there is propounded a view which is entirely at issue with 
that above stated ; but the support of it appears to me to 
amount to little more than mere surmise or to be based upon 
the facts of apospory, a rare phenomenon which we have 
every reason to regard as teratological : against it has to be 
placed the whole weight of evidence of descent of the arche- 
1 Jenaische Zeitschr., 1874, p. 69. 2 Pringsh., Jahrb., Bd. IX. p. 43, 1878, 
3 1- c., p. 69. * 1. c., p. 43. 
