Jan. I 9, 1 888] 



NATURE 



279 



and Hartig has found that its spores may lodge in cracks 

 in the barked logs of timber lying on the ground — cracks 

 such as those in Fig. i (seep. 182). In the particular 

 forests of which the following story, is told, the felling is 

 accomplished in May (because the trunks can then be 

 readily barked, and also because such work cannot be 

 carried on there in the winter), and the logs remain exposed 

 to the sun and rain, and vicissitudes of weather generally, 

 for some time. Now it is easy to see that rain may easily 

 wash spores into such cracks as those referred to, and the 

 fungus obtains its hold of the timber in this way. 



The next stage is sending the timber down to the 

 timber-yards, and this is accomplished, in the districts 

 referred to, by floating the logs down the river. Once in 

 the river, the wood swells, and the cracks close up ; but the 

 fungus spores are already deeply imprisoned in the cracks, 

 and have no doubt by this time emitted their germinal 

 hyphiE, and commenced to form the mycelium. This may 

 or may not be the case : the important point is simply 

 hat the fungus is already there. Having arrived at the 



11;. 19.— A piece of pine-wooJ attacked by the mycelium of Polvporus 

 vafior-arius. The timber has warped and cracked under the action of 

 the fungus, becoming of a warm brown colour at the same time ; in the 

 crevices the white strands of felt-like mycelium have ihen increased, 

 and on sp.itting the diseased timber they are found creeping and apply- 

 ing themselves to all the surfaces. E.xcept that the colour is snowy 

 white, instead of gray, this mycelium may easily be mistaken for 

 that of MeriiUus. The fructification which it develops is, however 

 very different. (After R. Hartig ) ' 



timber-wharves, the logs are stacked for sawing in heaps 

 as big as houses : after a time the sawing up begins. It 

 usually happens that the uppermost logs when cut up show 

 little or no signs of rot ; lower down, however, red and 

 brown streaks appear in the planks, and when the lower- 

 most logs are reached, perhaps after some weeks or 

 months, deep channels of powdery, rotten wood are 

 found, running up inside the logs in such a way that their 

 transverse sections often form triangles or V-shaped 

 figures, with the apex of the triangle or V turned towards 

 the periphery of the log. 



The explanation is simple. The uppermost logs on the 

 stack have dried sufficiently to arrest the progress of the 

 mycelium, and therefore of the disease : the lower logs, 

 however, kept damp and warm by those above, have 

 offered every chance to the formation and spread of the 

 mycelium deep down in the cracks of the timber. I was 

 much impressed with this ingenious explanation, given to 

 me personally by Prof. Hartig, and illustrated by actual 

 specimens. It will be noticed how fully it explains the 



curious shape of the rotten courses, because the depths 

 of the cracks are firit diseased, and the mycelium spreads 

 thence. 



Obviously some protection would be afforded if the 

 bark could be retained on the felled logs, or if they could 

 be at once covered and kept covered after barking ; and, 

 again, something towards protection might be done by 

 carting instead of floating the timber, when possible. At 

 the same time, this is not a reliable mode of avoiding the 

 disease by itself; and even the dry top logs in the saw- 

 yard are not sufe. Suppose the following case. The top 

 logs of the stack are quite dry, and are cut into beams and 

 used in building ; but they have spores or young mycehuin 

 trapped in the cracks at various places. If, from contact 

 with damp brick-work or other sources of moisture, these 

 spores or mycelia are enabled to spread subsequently, we 

 may have " dry-rot " in the building ; but this " dry-rot " 

 is due to Polyporus vaporarius, and not to the well-known 

 Merulius lacrynians. 



There can probably be no question of the advantage of 

 creosoting the ends of such rafters, beams, &c. ; since the 

 creosote will act long enough to enable the timber to dry, 

 if it is ever to dry at all. But the mycelium of Polyporus 

 vaporarius makes its way into the still standing timber of 

 pines and firs ; for it is a wound-parasite, and iti mycelium 

 can obtain a hold at places which have been injured by 

 the bites of animals, &c.; it thus happens that this form of 

 "dry-rot "is an extremely dangerous and insid'ous one, 

 and I have little doubt that it costs our Enghsh timber- 

 merchants something, as well as Continental ones. Nor 

 are the above the only kinds of " dry-rot " we know. 

 Hartig has described a disease of pine-wood caused by 

 Polyporus mollis, which is very similar to the last in many 

 respects, and the suspicion may well gain ground that this 

 important subject has by no means been exh:uisted yet. 



H. Marshall Ward. 



[ SCIENCE IN ELEMENTARY SCHOOLS> 



NOTHING could be more unsatisfactory than the 

 present position of the knowledge and teaching of 

 science in our elementary schools. Notwithstanding all 

 the advantages that have been offered to pupil-teachers 

 for the btudy of science, as a body they appear to be in a 

 most deplorable state in this respect. Though success in 

 the examinations of the Science and Art Department are 

 now taken into account in placing the students of the 

 training colleges for their teaching certificates, and 

 average school boys when they have been fairly taught 

 are quite competent for these examinations, yet very few 

 of the teachers have availed themselves of this privilege, 

 and it does not appear that the training colleges have 

 helped them in this respect. Very little, indeed, can be 

 expected while the ordinary pupil-teacher is described, as 

 he is in Mr. Cakeley's report on the working of the 

 Training Colleges, as deficient in many elementary 

 branches, notably mathematics. It is satisfactory, how- 

 ever, to notice that the quality of the candidates for 

 admission to the Training Colleges is improving, and 

 that these institutions are growing in teaching capa- 

 city and in popularity. The reports of the examiners 

 for admission are not, with regard to the subject 

 in hand, pleasant reading. Cne cannot expect good 

 answering in science from candidates who are quite 

 unable to paraphrase an ordinary piece of poetry, or to 

 explain a common English expression. Accordingly we 

 find that in Euclid, algebra, and mensuration, though a 

 few papers were especially meritorious, the vast majority 

 of the answers were very inferior. Few, if any, attempted 

 the easy riders in Euclid, and the examiner remarks that 

 he fears that the pupil-teachers receive but little assistance 



■"Report of Committee of Council on Educati, n (Eng'and ar J Wale X 



1S86-87." 



