1778 



Journal of Applied Microscopy 



distinct and firm wall was always found 

 around two sister spermatozoids, as shown in 

 Figs. 7 and 8. 



In the meantime the spermatozoids come 

 out into the wider chamber of the pollen- 

 tube, breaking the wall of the mother cell. 

 It is exceedingly fascinating to observe the 

 spermatozoids, like a pair of large infusoria, 

 swimming from one end of the tube to the 

 other (Fig. 9). 



The form of the spermatozoids is more or 

 less oval, somewhat like the shape of the 

 mature Ginkgo ovule, with a spiral marking, 

 bearing cilia on the upper end. The nucleus 

 is more hyaline and occupies a larger part of 

 the whole body. The surrounding cytoplasmic part is more granular and has an 

 oil-like globule of unknown nature (Figs. 9. Id). The size of spermatozoids 

 varies somewhat in individuals. The one measured by Mr. Hirase was 82/< 

 long by 49yU wide. According to Mr. Bessey "they are about I05x75-8'2yw 

 in size, with nucleus 71-75yM." Although I have not made very careful measure- 



FlG. 6. — Semi-diagratnatic section of 

 the upper part of the endosperm, 

 showing two archegonia [ar.], the 

 beak-hke process of the endosperm 

 (en.) supporting the remains of the 

 nucellus \nc.), and two pollen tubes 

 [pt.) ; X 24. — After Hirase. 



Fig. T. — Living spermatozoids in the mother cells (optical section): A. Spermatozoids are 

 gently vibrating the cilia and slightly moving their bodies ; B. Spermatozoids are moving 

 inside the mother cell, changing their relative positions ; about x 200. 



ment, judging from several figures of spermatozoids drawn b}- the aid of a 

 camera lucida, the size seems to vary from about 110 to 80yM in length, and from 

 50 to 85yw in width. The body of the spermatozoid is very movable, and 

 changes form by a slight pressure, resuming the normal form as soon as the 

 pressure is removed. 



I could not find even a trace of the so-called tail-like appendage. The 

 question naturally arises, what is the tail observed and figured by Mr. Hirase? 

 I myself had the privilege of examining his slide of the spermatozoid with an 



