52 JOURNAL OF THE [April, 



esting. They all contained more or less vegetable debris, some- 

 times as simple fibre, but oftener in, exceedingly fine scales, the 

 margins often showing well-defined geometric lines, and almost 

 suggesting epithelial scales. These would be commingled with 

 minute particles of wood, and mineral dust, the last prevailing. 

 There would occasionally be a lepidopterous scale from an ex- 

 tremely minute Tineidse Moth. 1 found also some vegetable 

 hairs, which polarized with fine effect. It should be mentioned 

 that these objects, animal, vegetable, ligneous and mineral were, 

 as a rule, utterly invisible to the unaided eye. 



A special word seems needed for the ligneous particles. No 

 artificial section can quite compare with some of these minute 

 ligneous abrasions. They are so delicate that the pitted cells, 

 which indicate their coniferous nature, are left in fine relief. A 

 section at best can only give us these cells with the other tissue 

 embedded between, but these look clear and separate, as if 

 the tissue had been peeled off, leaving the round cells in rows, 

 distinct as the peas in a pod. In like distinctness too, is shown 

 the spiral tissue. Under the polariscope these bits of wood, as 

 if they might be fortuitous preparations, are very elegant objects. 

 The pitted cells look like tiny buttons of brilliant ruby, while 

 the spiral tissue, blue as azure, seems to bind together fascines 

 of delicate rods of gold. From Maplewood to Bethlehem, for 

 over a mile in length, is a wooden walk ; and little think the 

 fair pedestrians that the abrasion by their feet gives to 

 the microscopist lignean dissections of such exquisite delicacy. 



In the home-slides I think the mineral matter was generally a 

 little coarser than that in the mountains. But it was greater in 

 amount, a fact to be expected, since in both places it is chiefly 

 road-dust, and in or near an old busy town one should expect 

 the quantity to be the greater. There is, however, a striking 

 difference between the vegetable catch of the two places. The 

 fibrous debris and the subtile exuviae of scales and cells, the 

 almost impalpable plant-dust is more plentiful, and the pollen 

 deposit incomparably greater. I have counted from two to 

 three hundred pollen-grains of Ragweed on one of these home- 

 slides. The amount would vary with the character of the day 

 — being, of course, the greater on dry days. 



This ragweed-pollen had to be borne some little distance, as 

 pains have been taken to extirpate the weed in my vicinity. It 



