164 PROCEEDINGS OF THE ACADElVrY OF [1887. 



One further point as to nibchods of collecting and I shall finish 

 this section of my subject. Unless our sponges are large, it is difficult 

 to detach them without mutilation, from the rough surfaces of 

 stones. It is therefore preferable to gather, when possible, those 

 growing upon wood, which may be scraped or chipped without 

 injury to them. It is essential to secure the very lowest portions, 

 as it is there the gemmules often abide. 



The proper season for collecting fresh water sponges, in waters of 

 the temperate zone, depends upon the purpose of the collector. If 

 it is his desire to gather cabinet specimens merely, for the iden- 

 tification of old or the determination of novel species, it is hardly 

 worth while to begin before July. As with the flowering of plants, 

 the maturity of different species of sponges is attained at various 

 ■dates, between mid-summer and late in November. The essential 

 point is, that the gemmules and their armature shall be fully 

 perfected; and w^hen that condition is attained in any specimen, 

 there is no reason for further delay. 



I would, however, recommend to intending students a far higher 

 object for their ambition ; — that is, the study of the physiology and 

 life history of sponges as members of a sub-kingdom whose position 

 has been greatly questioned and whose character, derivation and sub- 

 sequent evolution are very important and perplexing topics. I 

 would have such workers search for and examine them at all seasons 

 of the year, (even in midwinter, when I have never failed in suita- 

 ble situations to find some in a growing condition), keeping memo- 

 randa as to ea^ species separately ; noting the date of their germi- 

 nation or earliest appearance, the locality, elevation, temperature; 

 rapidity of growth at different seasons ; time and manner of forma- 

 tion of gemmules ; stability or decadence during the winter ; modes 

 of distribution and progression, whether always down stream or by 

 other more adventitious methods ; what becomes of the gemmules 

 upon reaching salt-water, and the thousand and one problems that 

 go to make up the life hietory of any animal form, and that, in this 

 instance, have been very little studied. I am jjarticularly anxious 

 that some competent person should undertake their study in the 

 briny, brackish and the fresh water lakes, pertaining to what is 

 known as the "Great Basin of the West," with a sjjecial view to as- 

 certain the conditions under which tliey form "protected gemmules" 

 in such localities. By tliis means, light may possilily be thrown 

 upon the pi'oblem of their possible derivation from the marine sponges. 



