304 
Di L. SOÓS 
12. rajz. Még fejlettebb spermatida elülső része. BouiN-féle pikrinformol, 
Heidenhain. 
13. rajz. Spermatida elülső része a perforatoriummal. BouiN-féle pikrinformol, 
Heidenhain. 
14. rajz. A fejlődés vége felé közeledő spermatida. Chromídiák már csak a 
sejt hátulsó végében vannak. BouiN-féle pikrinformol, Heidenhain. 
15. rajz. Majdnem teljesen fejlett spermatozoa feje. BouiN-féle pikrinformol, 
Heidenhain. 
16. rajz. Ugyanaz, mint a megelőző rajz. BouiN-féle pikinformol, Heidenhain. 
17. rajz. Teljesen fejlett spermatozoa testének elülső vége. FLEMMiNG-féle 
chrom-osmium-eczetsav (az erősebb ötszörösen hígítva), Heidenhain. 
18. rajz. A fejlődés késői szakaszában lévő spermatia testének hátulsó vége. 
A distalis centriola két egyenlő részre oszlott. BouiN-féle pikrinformol, Heidenhain- 
The original purpose of these observations was to clear up, if 
possible, the mode of reduction of Helix, which has been variously 
explained by vom Bath, Bolles Lee, Prowazek and Ancel. But in work¬ 
ing, it became evident that the species used was in many respects very 
appropriate for making observations in the changes of plasm and chro¬ 
matin during the growth period, which changes are, as I believe, more 
important than the reduction itself, therefore I paid particular attention 
to them. A short chapter is devoted to the development of the sperma¬ 
tozoa which also contains, I believe, some new and useful contributions. 
Methods. The following investigations are based upon observa¬ 
tions made on fixed and living material. This latter was taken from the 
living animal, stretched as much as possible upon coverglass. A number 
of fixing fluids were tried, namely : Concentrated sublimate, sublimate- 
alcohol-acetic acid mixture, Perényi’s and Mayer’s fluids, Bouin’s picric- 
formol, and Flemming’s chromic-osmic-acetic mixture (weaker and stron¬ 
ger). The best preparations were obtained with the two last mixtures. 
Flemming’s fluid preserved all parts of the cell very well; Bouin’s 
picric-formol was not less valuable than Flemming’s fluid, it preserved 
excellently the chromatic figures, but fixed insufficiently the chromidia 
of the cytoplasm. Mayer’s fluid was also useful, and so was in some 
respects sublimate and Perényi’s mixture, but the preparations made 
with these two last mixturers were so much inferior to those made 
with Flemming’s and Bouin’s fluids that in later preparations they have 
not been used. 
The material was imbedded in paraffin, the sections were cut 
into 4 to 7 mi era, generally 4. 
A number of staining methods have been employed, the most 
