374 APPENDIX. 



cles of male and female plants. If another species than Fucus 

 vesiculosus is used (e.g., F. platycarpus) both sex-organs will be 

 found in same conceptacle. If the sexes were not collected 

 separately and marked they can only be recognized after cutting 

 sections by the descriptions and figures given. Observe 



ii. The form and size of conceptacles. Compare with hair 

 pit. 



12. In male conceptacles, the crowded and tufted hairs, some 

 of whose terminal cells are spermaries. (If 381, figs. 309, 310.) 



13. In female conceptacles, the ovaries of various sizes. The 

 larger ones are mature. (If 389, figs. 324, 326, 327.) 



14. Demonstration. Mount very thin sections of male and 

 female conceptacles or some of the teased out hairs from them 

 and show: 



The oval spermaries, filled with rounded sperms. 

 The ovaries, young and old ; in the latter, the eight crowded 

 and therefore angular eggs, which round off on escape.* 



II. FUNGI. 



A. BLACK MOLD {Rhizopus nigricans). 



Before any white or black dots appear on the mold, examine 

 the vegetative hyphce. (^[ 48.) These are of two kinds, (a) those 

 running over the surface of the bread ; (o) those penetrating it. 



1. Examine a. Lift up a few threads with a needle and mount 

 them in water. Study with a lens. Are they white or colorless? 

 Why then is the body composed of them (the mycelium, ^[ 50) 

 white ? 



2. Examine b. With needles tease out hyphae from a bit of 

 bread in water ; free them as far as possible from the debris and 

 mount. Compare with a. 



After mold has begun to show black dots {sporangia) examine. 



3. Determine how the branches are placed which bear the spo- 

 rangia. (Fig. 49.) 



4. Compare the white (young) and black (mature) sporangia. 

 Can you find the very smallest ones ? 



* If fresh material can be obtained demonstrate the sperms and eggs after escape from 

 spermary and ovary. Expose a plant with mature receptacles which has been in sea 

 water (or a 3 per cent, solution of sea salt) to the air for a few hours; mount in sea 

 water on a slide some of the orange exudation which appears at the mouths of male con- 

 ceptacles. The water will be found filled with spermaries from which are escaping 

 motile sperms. The same treatment with female plants will demonstrate the eggs. By 

 mixing drops of water containing sperms and eggs the process of fertilization may be 

 watched. 



