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i' 



I 



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1907] . PACE— FERTILIZATION IN CYPRIPEDIUM 



357 



and the two new nuclei are being organized. Not only has the 

 embryo sac increased enormously in size, but the whole o\TiIe is very 

 active. The integuments haA^e grown very rapidly^ having lengthened 

 until they reach far beyond the nucellus. 



The usual egg apparatus, with its two synergids and egg, each with 

 very distinct cytoplasm and Hautschicht^ is organized in the micro- 

 pylar end of the sac, the other nucleus being left in the center or toward 

 the antipodal end (figs, zg^ jo), 



A few peculiar or ^^abnormal" forms were found. Fig. ji shows 

 what appears to be two mother cells, which is suggested by the unusual 

 development of that region of the o\aile compared with that of the 

 integuments and the remainder of the OA-ule; but the best evidence 

 is in the chromosomes, which in both cells appear to be of the hetero- 

 typic form. In another orchid^ in several cases, two mother cells (in 

 synapsis) were seen in a single ovule. Usually the spindle in the division 

 of the mother cell is parallel wdth the axis of the ovule; but fig. 32 

 shows one at right angles to the usual position; only two of these 

 spindles were seen, and they were near each other in the same ovary. 

 No arrangement of megaspores seen could be related to this position of 

 the spindle. Several examples of the division of both daughter cells 

 were found {fig. jj). It is probable that in this case only one embryo 

 sac is formed, for even in the very early spirem stage the two chalazal 

 megaspores are developing at the expense of the others, or at least 

 more rapidly than the two micropylar ones {fig. 34). The width of 

 the ovule in fig. jj suggests the possibility of a transverse spindle, 

 but it was evidently transverse in the second di\asion, as suggested by 

 the lines of protoplasm and by the position of the nuclei. These 

 ''abnormahties" are all rare in my material, not more than a dozen 

 such cases appearing among thousands of the usual forms. 



FERTILIZATION 



immense 



thenogenesis, or of failure to develop an embryo at all. The latter 

 view is favored by the wxll-known difficulty in germinating orchid 

 seeds, but the material studied gave no indication of either condition. 

 All OTOles of the right age had embr}^os, and in almost all of them 

 evidences of the pollen tube were more or less distinct, traces of it 



