SPIROGYRA QUININA. 41 



The starch is imbedded in the chlorophyll bodies, and 

 is quite distinct from the pyrenoid, although the con- 

 stancy in the relative position of the two would indi- 

 cate some connecting influence. The pyrenoids have 

 been long known and variously interpreted, 7 but the 

 recent careful studies of Schmitz 8 show that they are 

 quite analogous to nucleoli, especially in chemical 

 constitution and mode of multiplication. They are 

 only found in some of the algae and in a few higher 

 plants. 



It is when we examine the fruiting of Spirogyra, 

 that its great advancement beyond the simple forms 

 of the protophytes becomes apparent. We meet at 

 once with a true sexual process, which although very 

 simple is yet clearly defined and easily traced. This 

 process, as indeed in all other instances however mod- 

 ified, consists essentially of the intimate union of the 

 protoplasm (especially of the nucleus 9 ) of one cell with 

 that of another, which after a longer or shorter period 

 results in the production of a new individual. Usually 

 in higher groups there is a marked difference in size, 

 and we may conclude in other less apparent respects, 

 between the protoplasm which is fertilized, the female 

 element, and the protoplasm which fertilizes it, the 

 male element. In Spirogyra a slight difference between 

 the two elements, especially in size, has been pointed 

 out by DeBary, 10 Wittrock," and more fully by Ben- 



7 Hofmeisterin Die Lehre von der Pfianzenzelle (1867), p. 370, calls 

 them vacuoles. 



8 Die Chromatophoren der Algen (1882), p. 37 etseq. ; Quart. Jour. 

 Micr. Sci. , xxiv, p. 246. 



9 Cf. Strasburger, Neue Untersuchungen, p. 80. 

 10 Untersuchungen Uber die Familie der Conjugaten, 1858, p. 4. 

 "Quart. Jour. Micr. Sci., 1873, p. 123. 



