1290 
then floated loose in the preparation causing a bluish spine when 
the light fell through it. There appeared to be starchgrains among 
them, reaching the size of a small sterile pollengrain. 
But moreover, numerous elliptic pollengrains occurred that had 
germinated, not with a normal pollen-tube however, but with a 
tube that had rather the shape of a bubble. This bubble was 
sometimes smaller than the pollengrain itself, but often it was much 
larger. It contained 2, 3, 4, 5 or more globe-shaped nuclei. 
The closed anthers were slightly shrivelled, and the violet antho- 
eyanin in their walls was slightly discoloured. 
This observation stimulated me to try and find out whether in 
literature any mention was made of phenomena like those observed 
by me. I then, indeed, found that NEmrc (1898) had already observed 
the same thing, also in the hyacinth. He however, had discovered it 
in the partly petaloid anthers of a variety with double flowers. The 
anthers were taken by him from young closed flower-buds, fixed, 
bedded in paraffine, coloured, and made into microtome-series. He 
also found the small sterile pollengrains without reservesubstance, and 
the large, globe-shaped ones full of starchgrains. And here, too, 
many pollengrains had developed in the closed anthers pollen-tubes 
that often looked like large bubbles. He sometimes saw 8 nuclei 
in them. 
NEMEC supposed these deviations to be the consequence of the anthers 
being petaloid from the fact that I found them in the anthers of a 
single-flowered variety, one could infer that they were due to other 
causes than the flowers being double. | therefore thought the phenomenon 
was to be ascribed either to the peculiar bastardlike nature, of the 
variety Nimrod — as the latter is supposed to be a product of 
cross-fertilization between a French and a Dutch variety! — or to 
the occurrence of the deviating number of chromosomes in the 
somatic cells. 
I now resolved to examine the pollen of a large number of varieties 
Carefully I considered in what way this examination was to be 
performed, in order to derive the most favourable results from it. In the 
month of April and May 1919 I managed to perform it at Lisse, the 
centre of the Dutch hyacinth-cultures, in the following way. I chose 
varieties with the most diverging shapes, dimensions and flowering- 
times, double-flowered as well as single-flowered ones. Moreover I 
collected several times many racemes of one and the same variety, 
cultivated by different growers under greatly diverging circumstances. 
In this way I was able to come to palpable results. One of these 
results, in my eys the most important, may be mentioned here. 
