244 SCIENCE PROGRESS. 



such forms as Punctaria. There is here a great range of 

 different kinds of pit or cryptostoma developing in different 

 ways, and it may be objected that I am casting my net 

 too widely, and bringing together things that do not 

 sufficiently resemble each other. That will be justified or 

 not by further considerations ; in fact this diversity itself 

 will help us, I venture to think, to a better understanding 

 of the difficulties. It is characteristic of a laro-e number of 

 the olive-brown seaweeds to have hairs associated with 

 their sporangia or other reproductive bodies ; in fact the 

 sporangia are themselves morphologically hairs or branches 

 of hairs. The hairs that are sterile or vegetative, fulfil 

 among other functions that of furnishing protection or shelter 

 to the sporangia — protection it may well be against assaults 

 of minute animals and the like, or against the force of 

 currents that might prematurely detach the sporangia, or 

 even against excess of light. In the most simple fila- 

 mentous forms the hair -like branches themselves act in 

 this way, while the genera with stouter shoots have their 

 sporangia either immersed in the substance of the thallus, 

 or associated with dense tufts of hairs, or sunk in pits (con- 

 ceptacles). In short, they exhibit after one fashion or 

 another a tendency to conceal the developing reproductive 

 bodies. This tendency finds its highest expression in the 

 development of conceptacles, and we accordingly find in 

 the most highly differentiated order of the group, viz., the 

 Fticacecz, the most perfect example of conceptacle. 



If we may look for an illustration elsewhere of the view 

 I wish to state, it has been well said of the Ascomycetes, 

 among the fungi, that the flasked-shaped perithecium is the 

 same thing as the basin-, or flat disc-shaped apothecium 

 with the edges curled up. If we regard the sori of 

 olive -brown alga; in the same way, the conceptacle of 

 Splacknidium is much the same thing as a Laminarian sorus 

 with its edges curled up. I was so much impressed with 

 this simple view of the matter some years ago that it has 

 led me, with the help of fellow-workers, to make as minute 

 a study as material has permitted of the Laminarian sori 

 and cryptostomata, and of these bodies in other orders. 



