122 The Ohio Naturalist [Vol. VII, No. 6, 



oratory. A piece of damp, decayed wood should be selected 

 with a few crevices in it under which the insects may secrete 

 themselves. Put the insects in a good sized straight necked 

 bottle with a few bits of decayed leaves and dirt in the bottom. 

 The wood should be wedged in tight enough so that it will not 

 roll around and crush the insects. By keeping the wood a little 

 moist all of the time, and in a dark place most Thysanura will 

 thrive apparently quite as well as in their natural surroundings. 



THE DEVELOPMENT OF THE SPORANGIUM OF EQUISETUM 



HYEMALE.* 



LoN A Hawkins. 



The sporangium of Equisetum has been the subject of con- 

 siderable study. The first work of importance was by Hof- 

 meister who seems to refer the whole of the sporangium to a 

 single cell. Later Russow while A'erifying many of Hofmeister's 

 statements did not agree to this, but considered it to be of the 

 eusporangiate type, the sporogenous tissue as arising from the 

 division of a single cell but part of the walls and tapetum coming 

 from the surrounding tissue. This is now the generally accepted 

 view. 



Goebel (1) gives an account of the development of the 

 sporangium of E. palustre or E. limosufn which he illustrates with 

 two figures. According to this description it seems that the first 

 division of the sporangial initial is periclinal and separates the 

 primary sporogenous cell from the primary wall cell. In sub- 

 sequent development the primary sporogenous cell divides 

 much more rapidly than the other and we have a large mass of 

 sporogenous tissue formed while a segment of the rather thin 

 wall of the sporangium is all that comes from the pi^imary wall 

 cell. 



This is one of the points where Bower (2) disagrees with 

 Goebel. In his study of E. arevense and E. limosum he 

 came to the conclusion that Equisetum is eusporangiate; that 

 the contents of the sporangium are ultimately referable to a 

 single initial; that the first division is periclinal, the inner cell 

 and part of the outer going to form spores; and that the sporo- 

 genous tissue cannot be referred to a single cell as Goebel holds. 



Campbell (3) does not seem to agree with Bower either as to 

 the location of the superficial initial or as to its subsequent de\'cl- 

 opment. His account agrees more closely with that of Goebel. 

 There appears no statement of the species he studied but it was 

 probably E. telmateia. 



* Contributions from the Botanical Laboratory of Ohio vState 

 University XXX. 



