i8o 



HA R D WICKE ' S S CIE NCE- G O SSIP. 



owing to the fact that they occur in groups of four 

 which are arranged in a triangular manner, three at 

 the base and one at the top, so that whichever way 

 you cut through them only three spores are visible, 

 in any one section. 



Spores which occur in groups of four are termed 

 tetraspores. 



Microsporangia containing microspores are much 

 more commonly met with than sporangia containing 

 macrospores ; this is probably owing to their much 

 smaller size. The microspores are generally trian- 

 gular bodies, with raised convex ridges, though some 

 are somewhat oval in form. They, too, occur in 

 groups of four, and hundreds are contained in each 

 microsporangium. Considering the vast number of 

 these macrospores and microspores contained in our 

 coal-ball material, it is surprising how rarely traces 

 of the original cones to which they belonged have 

 been seen. While cones belonging to other species 



strata, but the "unexpected always happens," and 

 the result is this little insignificant-looking cone which 

 Professor Williamson estimates would not exceed an 

 inch in length when perfect. 



I have several slides containing these macro- and 

 microsporangia, and in one slide I have them asso- 

 ciated with a small portion of the original cone. 



Fig. io6 shows the form of the macrosporangia con- 

 taining three macrospores and a small part of the 

 fourth one. The sporangium is attached to a bract or 

 leaf of the cone, and its wall is composed of a single 

 layer of rectangular cells. 



Fig. 107 is a tangential section of a microsporangium 

 containing microspores, which occur in groups of 

 four, although, as is usually the case with these tetra- 

 spores, only three are visible in each group. Some of 

 the groups are broken up and the free spores are 

 scattered about in the sporangium. The specimen 

 also shows the network arrangement of the cellular 



Fig. 107. — Tangential section of a microsporangium, showing 

 microspores, X 112 diameters. 



Fig. 106. — A macrosporangium with macrospores, enlarged 

 60 diameters 



of lepidodendroid plants are not unfrequently met 

 with, yet this one has only been found in one instance. 

 This was discovered by Professor Williamson, in a 

 slide belonging to Mr. Isaac Earnshaw of Oldham, 

 and from material which he (Mr. Earnshaw) had 

 obtained from EUand, near Halifax. 



The specimen was shown to me by Professor 

 Williamson ; it is about one-third of an inch in 

 length, and contains both macrosporangia and 

 microsporangia — the macrosporangia being inter- 

 spersed irregularly amongst the microsporangia, 

 (which is also the case in the recent species, SelagincUa 

 Mai-tensii). 



This was a very different cone from what we had 

 been expecting to find. We had long been on the 

 look-out for the cone to which these large macrospores 

 belonged, fully expecting to find one of those magni- 

 ficent cones of about five or six inches in length, simi- 

 lar to some of those which occur in the Lowmoor coal 



tissues'forming the outside of the sporangium wall. 

 A transverse section across the centre would have 

 shown a similar arrangement of oblong cells as that 

 which is seen in fig. 108. 



The formation of beds of coal by spores. — Some 

 of the shales and coals of the coal formation are 

 remarkably rich in lepidostrobi and spores. The 

 shales overlying the Lowmoor Better Bed coal form 

 a rich repository of both, and the macrospores are so 

 large that they can be seen by the naked eye. These 

 are the spores which were alluded to by Professor 

 Huxley in his lecture "On a piece of Coal," as form- 

 ing the bulk of the "Better Bed Coal," and other 

 similar coals. But the learned Professor must either 

 have been misled or those who are most familiar with 

 that coal are strangely deceived. Being well ac- 

 quainted with the Better Bed coal and its surround- 

 ings, when we had read the lecture we accused our- 

 selves of carelessness in not having observed that it 



