7u8 EEPOKT — 1886. 



tluous spores will roll off, still leaving hundreds in the interstices of the first unglazed 

 paper. This should now be turned over on to the top of a pot, and rapped two or 

 three times with the end of a lead-pencil or the thumb-nail, when the spores will 

 be shaken off on to the fibre. The pot is now ready to be placed in the pan, and 

 when all the others have been prepared in the same way with the sanie or different 

 kinds of spores, the pan can be placed on a level shelf in a window facing the south, 

 and water that has been boiled poured in to the depth of half an ipch ; if the pots 

 contain spores of rock ferns only a quarter of an inch will do, but if there are pots 

 in the same pan some of which contain spores of the strong-growing kinds, and 

 some of the rock-growing kinds, place tbe pots containing the latter on pieces of 

 slate. This will prevent them from getting too wet. If the cover-glass is now put 

 on, all that will be requii-ed for the next three weeks or a mouth will be to place a 

 sheet of tissue paper before the glass during the midday sun, and if the bottom of 

 the pan becomes dry by evaporation add more water ; the water need not be boiled 

 after the spores have "germinated. After the spores have been sown from six to 

 twelve days, if the weather should be warm and bright, each pot can be examined 

 with a mao-nifying-glass, and in those containing spores of Osmunda, or Lastrea 

 Filix-mas, hundreds of small green specks will probably be seen, which from day to 

 day will increase in size until they meet and cover the surface with green leaf-like 

 prothalli. If they come in contactbefore each one has attained at least a quarter of 

 an inch in diameter the spores have been too thicldy sewn and must be thinned 

 out. Fronds will soon begin to appear, and will increase in number and size, each 

 successive frond larger and perhaps more complex than its predecessor. 



Sometimes a fungus attacks the prothalli in a pot. It first appears as a dark 

 spot, and gradually spreads until they are all destroyed. If seen in time it can be 

 stopped by heating some sand in an iron spoon and pouring some on tlie part 

 affected, but should the fungus pass through the soil and kill all the prothalli there 

 may still be some spores left that were unable to germinate in the first instance 

 on account of being too thickly sown ; these will soon make their appearance, and 

 the fungus will not attack the pot a second time. 



At any time in their development the prothalli can be lifted for examination,, 

 for this purpose preference being given to a fine ivory paper-knife. 



The necessary conditions for the growth of spores are light and heat without 

 direct smishine, moisture without stagnation, and the absence of competition from 

 plants of a stronger growth ; provided these conditions be present, ferns and other 

 spores can be grown in various ways for laboratory purposes. 



They can be grown on a thin piece of sandstone, a piece of slate, a lump of 

 peat, or a piece of glass. 



18. Life Cycles of Organisms reyresentecl diagrammatically and comparatively . 



By D. McAlpine. 



19. A Be- arrangement of the Divisions of Biology. By D. McAlpine. 



Sub-Section animal MORPHOLOGY. 



1. On the Theory of Sex, Heredity, and Reproduction. By Patrick Geddes. 

 In dealing with a subject naturally so obscure and so confused by conflicting 

 hypotheses as that of the nature and origin of sex, it is necessary to start with a 

 clear understanding that the required explanation must be not only in terms of 

 structure but of function, and must be satisfactory from the point of view of each 

 school of morphologists and physiologists in turn. Thus in any organism we must 

 not only note the general outward characters which may distinguish the sexes, and 

 correlate these with their habits of life, but follow them into the structures and 

 functions of the internal organs, and thence through the tissues to the egg-cells 

 and sperm-ceUs which respectively characterise the male and female. Below this, 

 however, a new problem arises; it does not suffice to observe these characteristic 



