OcTOBER 8, 1897.] 
stored food available for the roots and 
shoots, there was little, if any, dependence 
of one upon theother. Hering (96) comes 
to somewhat different conclusions as a re- 
sult of his experiments, finding that in some 
cases there was a slight increase of growth, 
while in others growth of the one was 
reciprocally retarded when the other was 
checked in development. Numerous cases 
of horticultural practice in pollination of 
fruits show that the form and size of the 
fruit and of the adjacent parts, as well as 
the longer or shorter period of existence of 
the floral envelopes, can be influenced by 
pollination. 
The investigations carried on by Klebs 
(96) in the conjugation of Spirogyra sug- 
gest how experimentation of this kind may 
be utilized to determine questions which in 
special cases cannot be arrived at easily by 
direct investigation. If threads of Spiro- 
gyra varians which are ready for conjuga- 
tion are brought into a. (0.5%) solution of 
agar-agar, in such a way that nearly 
parallel threads lie at a varying distance in 
their windings, where they are within cer- 
tain limits, the conjugation tubes are de- 
veloped and the zygospores are formed; 
but where the threads lie at too great a 
distance for the influence to be exerted, the 
cells remain sterile, and no conjugation 
tubes are developed. If, now, these threads 
be brought into a nutrient solution, these 
cells, which were compelled to remain 
sterile, grow and develop into new threads, 
2. €., they take on the vegetative, though 
they are fully prepared for the sexual func- 
tion. Strasburger (’97) has pointed out 
that this may be taken as excluding the 
possibility of there being a reducing di- 
vision of the chromosomes during the ma- 
turing of the sexual cells, a process which 
takes place in animals, and that the be- 
havior of Spirogyra in this respect agrees 
with what is known to take place in the 
higher plants, viz., that the reduction pro- 
SCIENCE. 
543 
cess is not one which is concerned in the 
maturity of the gametes. The same could 
be said of Polyphagus, in which Nowa- 
kowski (’78) found that before the zygo- 
spore was completely formed the protoplasm 
moved out and formed a new sporangium. 
In the case of Protosiphon botryoides 
Klebs was also able to compel the partheno- 
genetic development of the motile gametes, 
and the same thing was observed in the 
case of the gametes of Ulothriz. If we are 
justified in interpreting this phenomenon 
as Strasburger suggests, the evidence which 
Raciborski (’96) gives as a result of his 
experiments with Basidiobolus ranarum 
would support the idea that there is no re- 
ducing division in the chromosomes before 
the formation of the nuclei of the gametes. 
Raciborski found that in the case of the 
young zygospores of this plant, in old 
nutrient medium where the fusion of the 
plasma contents had taken place, but be- 
fore the nuclei had fused, if they were 
placed in a fresh nutrient medium the 
fusion of the nuclei was prevented, and 
vegetative growth took place, forming a 
hypha which possessed two nuclei, the pa- 
ternal one and the maternal one. Raci- 
borski interprets EKidam’s (’87) study of the 
nuclear division prior to the copulation of 
the gametes as showing that the reducing 
division takes places here as in the matura- 
tion of the sexual cells of animals, and 
looks upon the premature germination of 
the zygospore as showing that a paternal 
and maternal nucleus possesses the full pe- 
culiarities of a normal vegetative one. 
However, we are not justified in claiming a 
reducing division for the nuclei preceding 
the formation of the gametes in Basidi- 
obolus from the work of Hidam, since he was 
not able to obtain sufficiently clear figures 
of the division to determine definitely how 
many divisions took place, to say nothing 
of the lack of definite information as to the 
number of chromosomes. Fairchild (96) 
