Chromosomes in Pollen Mother-cells. 
337 
gamete possess all the characters of the species ? Or does the sperm, for 
example, contain characters not possessed by the egg ? Or does each gamete 
contain all the characters of the species, with some character, or characters, 
having a stronger potentiality in one gamete than in the other ? Among 
plants should any greater significance be attributed to variability in the 
size of the chromosomes in any individual than to the variability in the 
number of chromosomes in different species? A perusal of the recent 
literature on the subject shows one that the majority of theoretical dis- 
cussions concerning the transmission of hereditary characters embodies 
some answer to the above questions, which is either assumed in the 
beginning or developed in the course of the argument. 
Probably the prevailing view among botanists is that, in the chromatin 
of each parent or in each gamete, all the qualities are represented, for 
upon no other assumption does it seem possible to explain the partheno- 
genetic development of an egg into an individual similar to one arising from 
fecundation. Furthermore, in the case of an homosporous fern, for example, 
the spores contain only one-half the number of chromosomes of the 
sporophyte that bears them, yet the prothallia resulting from these spores 
produce both male and female gametes, which upon union develop 
into a sporophyte similar to the parent sporophyte. From these and 
numerous other cases, the only conclusion that can be drawn is that 
the reduced number of chromosomes, that is, those of any one gamete, 
contain all the characters of the individual. Strasburger (’ 05 , p. 59) seems 
to believe that the reduction division itself signifies the conclusion that 
before reduction all the primordia are present in duplicate, that is, double, 
while after reduction all occur single. ‘ Dass diese reduzierte Zahl die 
Anlage fur alle Merkmale des gegebenen Organismus in sich fasst, geht 
aus dem Wesen der Reductionsteilung hervor. Vor der Reductionsteilung 
waren alle Anlagen doppelt vertreten, nach der Reductionsteilung sind 
sie einfach vorhanden.’ 
In order that we may comprehend the significance of this doctrine, and 
to be able to draw our own conclusion, it is necessary to examine the 
data during every step in the reducing division. In the resting stage of 
the microspore mother-cell of Podophyllum or Lilium , for example, we can 
recognize definitely, let us say, only pangens, and while we cannot follow 
in every detail the construction of the spirem, and hence the chromosomes, 
out of these pangens, we may draw certain definite conclusions from those 
details that admit of objective demonstration, while other interpretations 
must remain problematical. Prior to the contraction into the balled-up 
mass, the chromatin may be rather finely and evenly distributed in the 
nuclear framework (Fig. 19). These fine granules may be regarded as 
pangens. On the other hand, the pangens may be collected into larger 
masses, each mass being usually much larger than a chromomere (Figs. 16, 
