1018] Altkuxatiux axl» Pautiiexogexesis IX Padixa 89 



viously to being shed. Table G would seem to show this. In this 

 case the same individuals used in series 3 were also used as a source 

 of eggs for series 9, 10, 11, and 13. In series 3, where the plants 

 had been kept separate from males for only 6 hours, we get males 14, 

 females 9, tetrasporic 30 — that is, tetrasporic individuals are gi'eatly 

 in excess; whereas in scries 9 we get males 59, females 61, tetrasporic 

 51. Here the female plants were separated from the males for 13 

 days. This gave sufficient time for the fertilized eggs attached to 

 the source plants to drop off before the experiment was begun. So 

 with series 10, where they had been kept 18 days. This procedure 

 was rendered possible after it was discovered that plants kept in the 

 laboratory, and well aerated by a method devised by Mast (5), would 

 continue for several weeks to produce eggs, so that the same plants 

 could be used as a source of eggs for quite a long time. Individual 

 cultures even in this table and some subsequent ones show variations 

 from this average which it is believed are sufficiently accounted for 

 by their location in the vicinity of other plants. 



Series 3 of Table 9 gives as a whole males 71, females 37, and 

 tetrasporic 23, a result entirely in line with the control cultures, and 

 is sufficient to show that unfertilized eggs are incapable of reproduc- 

 ing Padina in any one of its three forms, since the results produced 

 are clearly comparable co those secured in the controls. 



However, Series 6 of the same table gives males 71, females 50, 

 and tetrasporic 221. The great excess of tetrasporic plants in every 

 single culture of this series can be due only to previous fertilization. 

 Since the plants were here kept separate only two hours, it is highly 

 ])robable that a greater number of ]ierviously fertilized eggs were 

 still attached to the jnirent plants when rlie experiments were begun. 

 As this difficulty has entered into so many of the experiments a brief 

 test of it was made in 19 10. Female plants after having been kept 

 separate from males for 24 hours were allowed to discliarge tlicir 

 spores in tlie usual niiiiiner. The plants were then attachi'd t<i the 

 device already referred to (text iig. 1) for the purpose of dislodging 

 any fertilized eggs wihch might still b(> clinging to the iKircnf plants. 

 They were then moderately agitated for about one hour <mfe or twice 



